Yep, I solved the problem. The scripts I installed were too old for the patch or something similar. Thanks for your suggestion about the video.
Oh, and by the way...I don't know if somebody already suggested this, but I think you should add some prisoner transport missions in next version, using the stockade to take the inmates from a police station to another or to the jail. Of course, the bad guys would try to stop the truck and help their friend to evade the police.