In your esf file, theres a text document called mapcycle. You add the name of the map there. The names of the origional esf maps are there also.
For example, this is what the origional mapcycle document has in it:
esf_battlearena
esf_canyon
esf_cell_games
esf_cell_games_night
esf_city
esf_gero
esf_nameks_revival
esf_riverside
esf_rosat
esf_ToM
Now say you want to add....ape_city. Add that line to the list so it reads as:
esf_battlearena
esf_canyon
esf_cell_games
esf_cell_games_night
esf_city
esf_gero
esf_nameks_revival
esf_riverside
esf_rosat
esf_ToM
ape_city
I dunno why youre having problems with it, do you get any errors, or is the map just not showing up?