Unable to Print Image Using bitmapToHexadecimalString()

[idprime]

I am facing an issue with my code where I am attempting to print an image on a thermal printer using the bitmapToHexadecimalString() function. However, the image is not being printed on the paper. I would appreciate any assistance in identifying and resolving the problem.

Here is the code I am using:

    ThermalPrinter.bitmapToHexadecimalString({
         type: 'bluetooth',
         id: '00:11:22:33:44:55',
         base64: base64txt
     }, function() {
         alert('Successfully printed!');
     }, function(error) {
         alert('Printing error: ' + error);
    });