I'm having a strange glitch in black ops not allowing me to buy ghost pro?

Ok, so I have gotten all of the challenges needed to get ghost pro. I have destroyed a sentry gun, I have shot down 30 aircraft, and I have killed 20 people with a blackbird or spy plane. When I look at the challenges for it they all say complete, and I have 21 thousand dollars, so money is not the issue. But now that I have all of them, when I go to create a class, perk 1, and then ghost, typically it will say press x for ghost pro, but mine just says press x to view challenges for ghost pro. Has this happenned 2 any of u guys and how do u fix it?