A64 cannot load .d64, .t64 or .p00 files - only .prg. Magic64 can load and convert all these formats. I use Magic64 to convert these files to the C64 format (otherwise known as .prg) to be used by A64.
But sometimes A64 even has a problem loading the .prg format because the filename is not the same as the "internal filename" (or whatever it is). Then I use Magic64 (yet again) to make sure the names match by loading and resaving the .prg file. This always fixes the problem for me.
If you're really having problems, maybe I could convert some files for you. Don't expect many games to work properly with A64 though. I only got 5 or 6 games to work well enough to be playable.
