вы рисуете чёрный график на чёрном фоне.

вместо:
mainPain.AddList(sec.Symbol, sec, CandleStyles.BAR_CANDLE, 0, PaneSides.RIGHT);

напишете, на-пример:
mainPain.AddList(sec.Symbol, sec, CandleStyles.BAR_CANDLE, ScriptColors.Red, PaneSides.RIGHT);

ps
public static class ScriptColors
{
public static readonly Color AliceBlue = 0xFFF0F8FF;
public static readonly Color AntiqueWhite = 0xFFFAEBD7;
public static readonly Color Aqua = 0xFF00FFFF;
public static readonly Color Aquamarine = 0xFF7FFFD4;
public static readonly Color Azure = 0xFFF0FFFF;
public static readonly Color Beige = 0xFFF5F5DC;
public static readonly Color Bisque = 0xFFFFE4C4;
public static readonly Color Black = 0xFF000000;
public static readonly Color BlanchedAlmond = 0xFFFFEBCD;
public static readonly Color Blue = 0xFF0000FF;
public static readonly Color BlueViolet = 0xFF8A2BE2;
public static readonly Color Brown = 0xFFA52A2A;
public static readonly Color BurlyWood = 0xFFDEB887;
public static readonly Color CadetBlue = 0xFF5F9EA0;
public static readonly Color Chartreuse = 0xFF7FFF00;
public static readonly Color Chocolate = 0xFFD2691E;
public static readonly Color Coral = 0xFFFF7F50;
public static readonly Color CornflowerBlue = 0xFF6495ED;
public static readonly Color Cornsilk = 0xFFFFF8DC;
public static readonly Color Crimson = 0xFFDC143C;
public static readonly Color Cyan = 0xFF00FFFF;
public static readonly Color DarkBlue = 0xFF00008B;
public static readonly Color DarkCyan = 0xFF008B8B;
public static readonly Color DarkGoldenrod = 0xFFB8860B;
public static readonly Color DarkGray = 0xFFA9A9A9;
public static readonly Color DarkGreen = 0xFF006400;
public static readonly Color DarkKhaki = 0xFFBDB76B;
public static readonly Color DarkMagenta = 0xFF8B008B;
public static readonly Color DarkOliveGreen = 0xFF556B2F;
public static readonly Color DarkOrange = 0xFFFF8C00;
public static readonly Color DarkOrchid = 0xFF9932CC;
public static readonly Color DarkRed = 0xFF8B0000;
public static readonly Color DarkSalmon = 0xFFE9967A;
public static readonly Color DarkSeaGreen = 0xFF8FBC8F;
public static readonly Color DarkSlateBlue = 0xFF483D8B;
public static readonly Color DarkSlateGray = 0xFF2F4F4F;
public static readonly Color DarkTurquoise = 0xFF00CED1;
public static readonly Color DarkViolet = 0xFF9400D3;
public static readonly Color DeepPink = 0xFFFF1493;
public static readonly Color DeepSkyBlue = 0xFF00BFFF;
public static readonly Color DimGray = 0xFF696969;
public static readonly Color DodgerBlue = 0xFF1E90FF;
public static readonly Color Firebrick = 0xFFB22222;
public static readonly Color FloralWhite = 0xFFFFFAF0;
public static readonly Color ForestGreen = 0xFF228B22;
public static readonly Color Fuchsia = 0xFFFF00FF;
public static readonly Color Gainsboro = 0xFFDCDCDC;
public static readonly Color GhostWhite = 0xFFF8F8FF;
public static readonly Color Gold = 0xFFFFD700;
public static readonly Color Goldenrod = 0xFFDAA520;
public static readonly Color Gray = 0xFF808080;
public static readonly Color Green = 0xFF008000;
public static readonly Color GreenYellow = 0xFFADFF2F;
public static readonly Color Honeydew = 0xFFF0FFF0;
public static readonly Color HotPink = 0xFFFF69B4;
public static readonly Color IndianRed = 0xFFCD5C5C;
public static readonly Color Indigo = 0xFF4B0082;
public static readonly Color Ivory = 0xFFFFFFF0;
public static readonly Color Khaki = 0xFFF0E68C;
public static readonly Color Lavender = 0xFFE6E6FA;
public static readonly Color LavenderBlush = 0xFFFFF0F5;
public static readonly Color LawnGreen = 0xFF7CFC00;
public static readonly Color LemonChiffon = 0xFFFFFACD;
public static readonly Color LightBlue = 0xFFADD8E6;
public static readonly Color LightCoral = 0xFFF08080;
public static readonly Color LightCyan = 0xFFE0FFFF;
public static readonly Color LightGoldenrodYellow = 0xFFFAFAD2;
public static readonly Color LightGreen = 0xFF90EE90;
public static readonly Color LightGray = 0xFFD3D3D3;
public static readonly Color LightPink = 0xFFFFB6C1;
public static readonly Color LightSalmon = 0xFFFFA07A;
public static readonly Color LightSeaGreen = 0xFF20B2AA;
public static readonly Color LightSkyBlue = 0xFF87CEFA;
public static readonly Color LightSlateGray = 0xFF778899;
public static readonly Color LightSteelBlue = 0xFFB0C4DE;
public static readonly Color LightYellow = 0xFFFFFFE0;
public static readonly Color Lime = 0xFF00FF00;
public static readonly Color LimeGreen = 0xFF32CD32;
public static readonly Color Linen = 0xFFFAF0E6;
public static readonly Color Magenta = 0xFFFF00FF;
public static readonly Color Maroon = 0xFF800000;
public static readonly Color MediumAquamarine = 0xFF66CDAA;
public static readonly Color MediumBlue = 0xFF0000CD;
public static readonly Color MediumOrchid = 0xFFBA55D3;
public static readonly Color MediumPurple = 0xFF9370DB;
public static readonly Color MediumSeaGreen = 0xFF3CB371;
public static readonly Color MediumSlateBlue = 0xFF7B68EE;
public static readonly Color MediumSpringGreen = 0xFF00FA9A;
public static readonly Color MediumTurquoise = 0xFF48D1CC;
public static readonly Color MediumVioletRed = 0xFFC71585;
public static readonly Color MidnightBlue = 0xFF191970;
public static readonly Color MintCream = 0xFFF5FFFA;
public static readonly Color MistyRose = 0xFFFFE4E1;
public static readonly Color Moccasin = 0xFFFFE4B5;
public static readonly Color NavajoWhite = 0xFFFFDEAD;
public static readonly Color Navy = 0xFF000080;
public static readonly Color OldLace = 0xFFFDF5E6;
public static readonly Color Olive = 0xFF808000;
public static readonly Color OliveDrab = 0xFF6B8E23;
public static readonly Color Orange = 0xFFFFA500;
public static readonly Color OrangeRed = 0xFFFF4500;
public static readonly Color Orchid = 0xFFDA70D6;
public static readonly Color PaleGoldenrod = 0xFFEEE8AA;
public static readonly Color PaleGreen = 0xFF98FB98;
public static readonly Color PaleTurquoise = 0xFFAFEEEE;
public static readonly Color PaleVioletRed = 0xFFDB7093;
public static readonly Color PapayaWhip = 0xFFFFEFD5;
public static readonly Color PeachPuff = 0xFFFFDAB9;
public static readonly Color Peru = 0xFFCD853F;
public static readonly Color Pink = 0xFFFFC0CB;
public static readonly Color Plum = 0xFFDDA0DD;
public static readonly Color PowderBlue = 0xFFB0E0E6;
public static readonly Color Purple = 0xFF800080;
public static readonly Color Red = 0xFFFF0000;
public static readonly Color RosyBrown = 0xFFBC8F8F;
public static readonly Color RoyalBlue = 0xFF4169E1;
public static readonly Color SaddleBrown = 0xFF8B4513;
public static readonly Color Salmon = 0xFFFA8072;
public static readonly Color SandyBrown = 0xFFF4A460;
public static readonly Color SeaGreen = 0xFF2E8B57;
public static readonly Color SeaShell = 0xFFFFF5EE;
public static readonly Color Sienna = 0xFFA0522D;
public static readonly Color Silver = 0xFFC0C0C0;
public static readonly Color SkyBlue = 0xFF87CEEB;
public static readonly Color SlateBlue = 0xFF6A5ACD;
public static readonly Color SlateGray = 0xFF708090;
public static readonly Color Snow = 0xFFFFFAFA;
public static readonly Color SpringGreen = 0xFF00FF7F;
public static readonly Color SteelBlue = 0xFF4682B4;
public static readonly Color Tan = 0xFFD2B48C;
public static readonly Color Teal = 0xFF008080;
public static readonly Color Thistle = 0xFFD8BFD8;
public static readonly Color Tomato = 0xFFFF6347;
public static readonly Color Turquoise = 0xFF40E0D0;
public static readonly Color Violet = 0xFFEE82EE;
public static readonly Color Wheat = 0xFFF5DEB3;
public static readonly Color White = 0xFFFFFFFF;
public static readonly Color WhiteSmoke = 0xFFF5F5F5;
public static readonly Color Yellow = 0xFFFFFF00;
public static readonly Color YellowGreen = 0xFF9ACD32;
}