Creeps98

Hello! I have been working on a mission for a while now, where the players have to take a big town. To do so there are multiple goals and my plan was to provide the players with little rewards for completing certain tasks. One of the rewards was supposed to be a new artillery provider (helicopter or artillery) but i cannot make it work. The mission always starts out with the player group already having access to all the support. Is there any way of setting up a trigger or something that will cause new support units to become available? Thanks in advance!

Thanks! Works perfectly.