War ended and cant airlift (White Giant)

game master. i dont know what the problem is here but i got ripped off trillions of dollars. i was at war with a c3, took out air defenses and sent a air base const unit to build an air strip. it showed up but would not let me use it as a off air base. the result was no land forces. then i sent another and same problem. i have 3 sf units painting and now it says war ended. my problem is i needed the cash from the c3. now im in the neg and wont recover for some time. can you explain this to me and if im doing everything right how do i recover the loss. attacking country is slave on wg. thanks