IDXGISwapChain::CheckInterfaceSupport returns a result that cannot be

according to windows website the IDXGIAdapter::CheckInterfaceSupport returns S_OK if the passed in interface is supported and otherwise DXGI_ERROR_UNSUPPORTED. Code snippet:

for( size_t i = 0; i < GInterface::m_Adapters.size(); i++)
{
    hr = GInterface::m_Adapters.at(i)->CheckInterfaceSupport(__uuidof(ID3D11Device), (LARGE_INTEGER*)&umdVersion);
    printf( "***D3D11 %sSUPPORTED FOR ADAPTER %d (%d)",
            (hr != DXGI_ERROR_UNSUPPORTED) ? "" : "NOT ",
            i,
            umdVersion);
}

The console always prints NOT, but if I change to __uuidof(ID3D10Device) it does not.
But I definitely know that my GPU supports DirectX11, because:

1. The programm I am currently writing is using DirectX 11 and it's running
2. My GPU: GTX 970, not the newest, but... yeah should be supporting D3D11 :D

Can please somebody clear things up I am slightly irritated, thank you.