you need to use 24 bit .tga images or 24 bit .jpg images . If you use a .jpg leave the shader as is you have to say .tga but the game will also load .jpg if it does not find a .tga
I copied part of a texture from the pk3 file in MOH. It was a .jpg so I edited it and renamed it .tga. Maybe if I save it as a 24-bit bmp and then rename it .tga
You can't just rename a file with a different extension to convert it to that file type. The error you were given was saying your tga was in the wrong format. Re-naming a jpg to tga leaves it in jpg format but your O/S and Moh try and treat it as a tga but will fail to preform any operations on it.
Since you've already got it sorted this doesn't matter but I though I'd just mention it.
You can't just rename a file with a different extension to convert it to that file type.......Since you've already got it sorted this doesn't matter but I though I'd just mention it.