GraphicsMagick readImages ErrorFileOpen exception

Question

I'm using GraphicsMagick in my c++ application running on Raspberry Pi. All goes well, except the "readImages" function which returns an "Magick::ErrorOpenFile" exception:

terminate called after throwing an instance of 'Magick::ErrorFileOpen'
GraphicsMagick Error: Magick: Unable to open file () reported by magick/blob.c:3061 (OpenBlob)

This is my code:

#include <Magick++.h>
#include <iostream>
using namespace std;
using namespace Magick;

int main(int argc,char **argv){
    InitializeMagick(*argv);

    try {
      list<Image> imageList;
      std::string lFilename = "paars.jpg";

        try {
            // Attempt to read the image
            readImages( &imageList, lFilename );
            std::cout << "Image read successfully." << std::endl;

        } catch (Magick::Exception &e) {

            // Handle GraphicsMagick exceptions
            std::cerr << "GraphicsMagick Error: " << e.what() << std::endl;

        } catch (std::exception &e) {
            // Handle other exceptions
            std::cerr << "Error: " << e.what() << std::endl;
        }

    } catch (std::exception &e) {
        // Handle any other exceptions in the outer block
        std::cerr << "Error: " << e.what() << std::endl;
    }

    return 0;
}

I have tried with several different images and different formats like bmp, jpg and png, but I cannot get passed the exception. The path of the images is correct, I can read the image with an Magick::Image object like so:

    Magick::Image myImage( lFilename );

Any help would be greatly appreciated!