I've packed two of my Ra2 maps into an *.mix-file using the 'XCC MIX Editor' (told the program it was Ra2 maps) but they wont show in the map list, what am i doing wrong?
Maps should use .map not .mpr or .yrm (simply change the extension)
Maps in mix files are added to the map list by defining them in a PKT file. It is plain text and can have any name as long as it uses the .pkt file extension. Your PKT file must be loose (not in a mix), or it will not be read by the game. If using XCC mod launcher, your PKT file can be written on launch by putting in the video category.
In addition to Cannis' post, I'd like to add that you most definately should use XCC Mod Creator/Launcher - it makes things so much easier. Get it at xccu.sourceforge.net. Good luck.
If this ins't for a mod and you are just handing out your maps for people to download them, just have them in the RA2/ directory with a .yrm extension. The game will automatically handle it. However, if this if for a mod, you need to distribute your .csf (string file) so it has the strings.