SharpDx ShaderBytecode.FromFile() System.IndexOutOfRangeException

I am using DX11 and SharpDx.

I compile the hlsl file using:

fxc /T vs_5_0 /E VSMain "Minicube.hlsl" /Fo "$outputDir/Minicube.vs.fxo"
fxc /T ps_5_0 /E PSMain "Minicube.hlsl" /Fo "$outputDir/Minicube.ps.fxo"

Minicube.hlsl

cbuffer ModelViewProjectionConstantBuffer : register(b0)
{
    matrix worldViewProj;
};

struct VSInput
{
    float4 position : POSITION;
    float4 color : COLOR;
};

struct PSInput
{
    float4 position : SV_POSITION;
    float4 color : COLOR;
};

PSInput VSMain(VSInput input)
{
    PSInput output;

    output.position = input.position;
    //output.position = mul(input.pos, worldViewProj);
    output.color = input.color;

    return output;
}

float4 PSMain(PSInput input) : SV_TARGET
{
    return input.color;
}

I get further up to the signature line when it fails with: "Index was outside the bounds of the array"

    using (var vsByteCode = ShaderBytecode.FromFile(baseDir + "Minicube.vs.fxo"))
    using (var psByteCode = ShaderBytecode.FromFile(baseDir + "Minicube.ps.fxo"))
    {
        _vertexShader = new VertexShader(DeviceTarget, vsByteCode);
        _pixelShader = new PixelShader(DeviceTarget, psByteCode);

        _signature = ShaderSignature.GetInputSignature(vsByteCode);
    }

I am trying to enable the debug to get more info but can't seem to get more than that.