Why Does D3Dx11Createshaderresourceviewfrommemory Only Upload a Partial Copy of My Texture?

I have a problem with the D3DX11CreateShaderResourceViewFromMemory helper function.

I read some texture from a file or ZIP and pass the raw bytes and length to the helper function, however only part of the texture is uploaded (as confirmed by PIX). I tried fiddling with the length manually but to no avail. Here is the code that loads the texture from file:

struct FileDataLoader
{
    void Load()
    {
        std::ifstream file(mFileName);

        if (file)
        {
            file.seekg(0,std::ios::end);
            std::streampos length = file.tellg();
            file.seekg(0,std::ios::beg);

            mBuffer.resize(length);
            file.read(&mBuffer[0],length);
            file.close();
        }
    }

    void Decompress(void*& data, std::size_t& numBytes)
    {
        data = &mBuffer[0];
        numBytes = mBuffer.size();
    }

    std::wstring mFileName;
    std::vector<char> mBuffer;
};

FileDataLoader fdl;
fdl.mFileName = L"Content\\Textures\\Smoke.dds";
fdl.Load();
void* bytes;
std::size_t size;
fdl.Decompress(bytes, size);
DXCall(D3DX11CreateShaderResourceViewFromMemory(device, bytes, size, NULL, NULL, &particleTexture, NULL));

That is only a sample code that I am using to debug this problem, and I narrowed it down to the file loading and the D3DX helper function. Now if I do this instead:

DXCall(D3DX11CreateShaderResourceViewFromFileW(device, L"Content\\Textures\\Smoke.dds", NULL, NULL, &particleTexture, NULL));

it works perfectly fine.

Any idea on why it would not upload the texture entirely ?