Magick++ error with converting byte to Blob

Question

Good day,

I have a problem converting my pdf to images in magick++. I am quite confused if the problem is in the DLL of Magick++ because when I try it to another project all good but when I used the DLL, the error persists:

w3wp.exe: no decode delegate for this image format `' @ error/blob.c/BlobToImage/412

My code is

__declspec(dllexport) char* __stdcall Scan(BYTE * pdf, int nSize){
    Magick::Blob blob((const void *)pdf, nSize);
    try{
        Magick::ReadOptions options;
        options.density(Magick::Geometry(300, 300));

        std::list<Magick::Image> images;
        Magick::readImages(&images, blob, options);  //The error persists in here

        size_t i;
        std::list<Magick::Image>::iterator image;

        for (image = images.begin(), i = 0; image != images.end(); image++, i++){

        }
    }
}

I really appreciate any help, I am stuck on this one.