BMP icon shows up as black

Hello, I’m new. I have a program, I put in on SD into a folder along with an icon in bmp format named icon.bmp, just like other programs do, but in the main menu my program is shown with a completely black icon. If I switch the icon for the one of the other programs, it shows up okay. I am exporting my icon from GIMP, have tried various formats including 565. How do you create these icons so that they work? Thanks for help!

OK solved, had to hexdump both images and compare individual bytes. When exporting from GIMP, check “do not export color information” under “Compatibility options” and “24 bits R8 G8 B8” under “Advanced options”. This information should probably be somewhere in an official tutorial.