Shader runs in OpenGL, but crashes in DirectX

[PixieCatSupreme]

I have a shader that builds and runs fine when working with an OpenGL project, but crashes when loaded in a DirectX project. It does build, but when loaded it crashes and gives an Invalid Arguments exception. It does not tell me which argument is invalid.

#if OPENGL
#define SV_POSITION POSITION
#define PS_SHADERMODEL ps_3_0
#define VS_SHADERMODEL vs_3_0
#else
#define PS_SHADERMODEL ps_4_0
#define VS_SHADERMODEL vs_4_0
#endif

sampler2D TextureSampler : register(s0);

struct VertexShaderOutput
{
float4 Position : SV_POSITION0;
float4 Color : COLOR0;
float2 Tex : TEXCOORD0;
};

matrix Projection;

struct VsInput
{
float4 Position : POSITION0;
float4 Color : COLOR0;
float2 TexureCoordinateA : TEXCOORD0;
};

VertexShaderOutput MainVS(VsInput input)
{
VertexShaderOutput output;
output.Position = mul(input.Position, Projection); // Transform by WorldViewProjection
output.Color = input.Color;
output.Tex = input.TexureCoordinateA;
return output;
}

float4 MainPS(VertexShaderOutput input) : COLOR
{
float4 color = tex2D(TextureSampler, input.Tex);
float average = (color.r + color.g + color.b) / 3;

average = int(average * 25) / 25.0;

color.rgb = average;
return color;

}

technique BasicColorDrawing
{
pass P0
{
VertexShader = compile VS_SHADERMODEL MainVS();
PixelShader = compile PS_SHADERMODEL MainPS();
}
};

I am using MonoGame 3.8.1.303.