i guess that his invek map does exist, but like what dastgir said, the problem is the .town he ddn't change the value of it, it will work if he follows what dastgir recommended to do.
using this script might help u in future when u decided to add extra/more maps less hassle.
//=========== Town Invasion ==========//=========== Version: 1.0 ===========- script towninvasion -1,{OnClock0800:OnClock1400:OnClock2000:OnClock0200: .rand$ = .maps$[rand(getarraysize(.maps$))]; announce "A Boss is destroying our "+.rand$+" city! Help us!",bc_all,0x00FFFF; sleep2 2000; announce "Hurry before it dominate the whole "+.rand$+"!",bc_all,0x00FFFF; sleep2 5000; announce "This monster is quite elusive! So please beat it up!",bc_all,0x00FFFF; monster .rand$,0,0,"Bring it on!",1502,1,"towninvasion::OnInvadeKill"; end;OnInvadeKill: announce "Good job, for keeping our city safe!!",bc_all,0x00FFFF; getitem 7227,10; end;OnInit: setarray .maps$[0],"invek"; // Maps end;}