I've stared at this for at least half an hour now and I cannot figure out what directx is complaining about. I know this error normally means you put float3 instead of a float4 or something like that, but I've checked over and over and as far as I can tell, everything matches.

This is the full error message:

D3D11: ERROR: ID3D11DeviceContext::DrawIndexed: Input Assembler - Vertex Shader linkage error: Signatures between stages are incompatible. The input stage requires Semantic/Index (COLOR,0) as input, but it is not provided by the output stage. [ EXECUTION ERROR #342: DEVICE_SHADER_LINKAGE_SEMANTICNAME_NOT_FOUND ]

This is the vertex shader's input signature as seen in PIX:

// Input signature:
//
// Name                 Index   Mask Register SysValue Format   Used
// -------------------- ----- ------ -------- -------- ------ ------
// POSITION                 0   xyz         0     NONE  float   xyz 
// NORMAL                   0   xyz         1     NONE  float       
// COLOR                    0   xyzw        2     NONE  float      

The HLSL structure looks like this:

struct VertexShaderInput
{
    float3 Position : POSITION0;
    float3 Normal : NORMAL0;
    float4 Color: COLOR0;
};

The input layout, from PIX, is:

The C# structure holding the data looks like this:

[StructLayout(LayoutKind.Sequential)]
public struct PositionColored
{
    public static int SizeInBytes = Marshal.SizeOf(typeof(PositionColored));

    public static InputElement[] InputElements = new[]
    {
        new InputElement("POSITION", 0, Format.R32G32B32_Float, 0),
        new InputElement("NORMAL", 0, Format.R32G32B32_Float, 0),
        new InputElement("COLOR", 0, Format.R32G32B32A32_Float, 0)
    };

    Vector3 position;
    Vector3 normal;
    Vector4 color;

    #region Properties
    ...
    #endregion

    public PositionColored(Vector3 position, Vector3 normal, Vector4 color)
    {
        this.position = position;
        this.normal = normal;
        this.color = color;
    }
    public override string ToString()
    {
        StringBuilder sb = new StringBuilder(base.ToString());
        sb.Append(" Position=");
        sb.Append(position);
        sb.Append(" Color=");
        sb.Append(Color);
        return sb.ToString();
    }
}

SizeInBytes comes out to 40, which is correct (4*3 + 4*3 + 4*4 = 40). Can anyone find where the mistake is?