WRWBO

Im not sure if I should open another topic about this, but this seems as good of place as any. I just went into my military to make a aircraft change, and deleted 20 of my 8 strength aircraft, to upgrade totally to 9 strength aircraft. But for some reason now it won't let me purchase anything higher than 3 strength aircraft lol. I have 110 tech and 1160 infra, with plenty of money, so I don't what the problem is. Any suggestions?