I'm new to the program and don't have ti completely working either but from what I can see, there may be a few issues. For one, newer versions of the mgmaps program don't include google maps as a format so that may be an issue as the gmapmaker only works on google maps.
Secondly, from reading on this forum, someone said that instead of typing the root folder and then the folder where you have your maps as the path, you instead use the name of your SD card and then the folder name. For example, instead of mmc/mmca1/mgmapscache, if your card's name was "transflash" (like mine), you would type transflash/mgmapscache. Try that maybe. But as I said, I haven't gotten it to work yet either so I may be way off!!
