Spring RTS Engine

I'm not sure if this is in the right place, but i definately need some help here.

I seem to have encountered a problem installing new maps into spring. When i unzip them into the maps folder all goes well but in game (i only play single player) i only have 24, maximum. If i attempt to delete an old one and reinstall a new one, the old map is still listed in the fixed number of 24 and the new one doesnt exist. I have the latest version of spring and am quite stumped with this problem. Any help would be most appreciated, thanks

For possible interest i play using the "Spring Single Player 0.5" thing which i actually got when i first started playing some time ago.

If you get maps as .sdz or .sd7 file you should not unzip them, just put them in the maps folder.