help.

Hi, Wanted to show within a command mes "", the sum of online players in 3 maps.   Maps Are: ice_dun01 ,  ice_dun02, ice_dun03 *Wanted to know if the following command is right.   set @on_orcsdun,"+(getmapusers("orcsdun01.gat"))+(getmapusers("ice_dun02.gat"))+(getmapusers("ice_dun02.gat"))"...