when the galaxyforge map was in the galaxyforge folder in the my documents/my games area did you check the galaxyforge map type?
and here is my standard advice regarding maps in sins/ent/dip/trinity & rebellion
assuming you have sins 1.193/entrenchment 1.053/diplomacy 1.34, the galaxy forge maps NEED to be placed here for xp
C:\Documents and Settings\'user name'\Local Settings\Application Data\Ironclad Games\Sins of a Solar Empire\GalaxyForge
or for vista/windows 7
C:\Users\'user name'\AppData\Local\Ironclad Games\Sins of a Solar Empire\GalaxyForge.
for rebellion.80 and later the new path is
My Documents\My Games\Ironclad Games\Sins of a Solar Empire Rebellion\GalaxyForge
these paths assume that your windows installation is on the C: drive and the user space(xp documents and settings,vista/7 users is also on the C: drive, just substitute the drive letter for your fully qualified path to your documents folder)
for sins 1.15/entrenchment 1.00 and earlier, the correct location IS the program files \galaxy folder, and you also NEED to edit the entrenchment's galaxy.manifest to include the maps and also the total count of maps
NOTE the first two folders after the 'user name' are hidden , so to see them you must first click on 'tools' then 'folder options', then 'view', then click on 'show hidden files& folders' then click ok, then you will be able to browse your want to the folder. I suggest when you find the folder that you create a shortcut to it on the desktop
NOTE 2 the 'user name' in the above paths is your WINDOWS login user name, eg Administrator
also the galaxy forge maps in the local apps galaxyforge folder only show up in the galaxy forge tab of map types in sins 1.16+/entrenchment 1.02+
if the map IS a galaxy forge and giving the instant win/loss screen then MAKE sure that EACH player has a home planet and is not for a particular mod that has extra home planets and stars
if the galaxy forge map is placed in the program files galaxy folder, then the map NEEDS to be manually added to the entrenchment & diplomacy galaxy.manifests(not recommended as EACH update will replace any files that are different or have been changed)
and if a map you want to play was released before 25th feb 2009 OR created with an earlier version of galaxyforge than version 3 then you will also need the sins map updater from here
there is a second type of map which SHOULD be placed in the mapdesigner folder, you can tell if it is by the eighth line reads randomizeStartingPositions TRUE', if this line is FALSE then it is a galaxyforge map and could be in an older map format. the current map format version is 3 this can be seen in line two of the file. if the map is a version 0,1 or 2 then the map updater will make it playable in current versions and expansions
the differences between map versions0,1 & 2 were only the addition of ONE line near the start of the file each, BUT mapversion3 has 5 new lines PER PLANET/player & template and 5 changed lines per planet/player & template and WILL CAUSE THE minidump/freeze curse if you just change the version number.