Hi, for some reason when i call ID3D10Device::CreateInputLayout it fails but ID3D10Device1::CreateInputLayout succeeds? Any idea what could be the problem? It fails with E_INVALIDARG.

VOID
CreateInputLayout( ID3D10Device* Device )
{
    HRESULT hr;
    ID3D10Blob *compiledFx = 0, *errorMsgs = 0;
    ID3D10Effect *effect;
    ID3D10EffectPass* effectPass;
    ID3D10EffectTechnique* effectTechnique;
    D3D10_PASS_DESC passDesc;
    
    D3D10_INPUT_ELEMENT_DESC layoutDesc[ ] =
    {
        { "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D10_INPUT_PER_VERTEX_DATA, 0 },
        { "TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT, 0, 12, D3D10_INPUT_PER_VERTEX_DATA, 0 },
        { "COLOR", 0, DXGI_FORMAT_B8G8R8A8_UNORM, 0, 20, D3D10_INPUT_PER_VERTEX_DATA, 0 }
    };
    
    CHAR effectFile[ ] = \
    "Texture2D SpriteTex;"
    "SamplerState samLinear {"
    "     Filter = MIN_MAG_MIP_LINEAR;"
    "     AddressU = WRAP;"
    "     AddressV = WRAP;"
    "};"
    "struct VertexIn {"
    "     float3 PosNdc : POSITION;"
    "     float2 Tex    : TEXCOORD;"
    "     float4 Color  : COLOR;"
    "};"
    "struct VertexOut {"
    "     float4 PosNdc : SV_POSITION;"
    "     float2 Tex    : TEXCOORD;"
    "     float4 Color  : COLOR;"
    "};"
    "VertexOut VS(VertexIn vin) {"
    "     VertexOut vout;"
    "     vout.PosNdc = float4(vin.PosNdc, 1.0f);"
    "     vout.Tex    = vin.Tex;"
    "     vout.Color  = vin.Color;"
    "     return vout;"
    "};"
    "float4 PS(VertexOut pin) : SV_Target {"
    "     return pin.Color*SpriteTex.Sample(samLinear, pin.Tex);"
    "};"
    "technique10 SpriteTech {"
    "     pass P0 {"
    "         SetVertexShader( CompileShader( vs_4_0, VS() ) );"
    "         SetGeometryShader( NULL );"
    "         SetPixelShader( CompileShader( ps_4_0, PS() ) );"
    "     }"
    "}";


    D3DCompile(
        effectFile, 
        strlen( effectFile ), 
        0, 
        0, 
        0, 
        "SpriteTech", 
        "fx_4_0", 
        0, 
        0, 
        &compiledFx, 
        &errorMsgs
        );


    D3D10CreateEffectFromMemory(
        compiledFx->GetBufferPointer(),
        compiledFx->GetBufferSize(),
        0,
        Device,
        NULL,
        &effect
        );


    compiledFx->Release();


    effectTechnique = effect->GetTechniqueByName( "SpriteTech" );
    effectPass = effectTechnique->GetPassByIndex(0);


    effectPass->GetDesc(&passDesc);
    
    hr = device->CreateInputLayout(
        layoutDesc,
        sizeof( layoutDesc ) / sizeof( layoutDesc[ 0 ] ),
        passDesc.pIAInputSignature,
        passDesc.IAInputSignatureSize,
        &inputLayout
        );


    if (FAILED(hr))
    {
        OutputDebugStringW(L"ID3D10Device::CreateInputLayout failed!");
        //return;
    }
}

I can't make it any simpler than this

{ "COLOR", 0, DXGI_FORMAT_B8G8R8A8_UNORM, 0, 20, D3D10_INPUT_PER_VERTEX_DATA, 0 }

According to this page, it would seem that DXGI_FORMAT_B8G8R8A8_UNORM is not available for D3D10. I'd guess that you'd have no trouble not using a 10.1 device if you used the R8G8B8A8_UNORM (or something similar that's acceptable for your needs) format instead.

{ "COLOR", 0, DXGI_FORMAT_B8G8R8A8_UNORM, 0, 20, D3D10_INPUT_PER_VERTEX_DATA, 0 }

According to this page, it would seem that DXGI_FORMAT_B8G8R8A8_UNORM is not available for D3D10. I'd guess that you'd have no trouble not using a 10.1 device if you used the R8G8B8A8_UNORM (or something similar that's acceptable for your needs) format instead.

That worked. A big thanks to you both.