Can't buy block buster because it is grayed out in pet rescue saga

TCMS3812

I use Facebook to play Pet Rescue Saga and I have a lot of coins to use but when I go to a level, I am unable to buy the block buster because it is always grayed out. How do I buy them?  I am on level 127.

KingsPinn

I heard from a friend that if you go back and play the first block buster level (level 11 I think) then it unlocks again. Could be worth a try I guess?