Hey, I bought dogfight the other day, and it tells me to "upgrade" and when I click on the upgrade button,
Nothing happens. Also, when I go to mission select, it tells me to upgrade for more levels and multiplayer. I click on THAT and it takes me to iTunes store, and directs me to dogfight, which I already bought, and it says installed instead of the price. PLEASE HELP

Apple is having trouble with their in-app payment system. That's why when you hit "upgrade" nothing happens. I've been sending them emails for a couple days but nobody replies... as soon as they fix it, a new update should be available for the game. Check the itunes store from time to time to see whether it's out already
It should be out as version 4.0.14

Hi. I have this same problem. I bought the app last October. I can't now get past level 1 and have the same upgrade / already installed problem as Zuperman. Is this still not resolved?

apple is missing in action... no clue what's going on.
anyway, did you remove the application and then install it again? that's the only way you can lose your game information.

Hi. I've uninstalled and reinstalled a number of times now. I still cannot use the game. This is not happening on any of the other games on my ipad.

yes that's a problem. If you "remove" the game and install it again, you lose all the data attached to it.
I can connect you to multiplayer and recover your multiplayer data but there is no way for me to know what you did on "solo" mode.

Hi. That is not my problem. I can't play because the ap tells me to upgrade but when I click on upgrade nothing happens. If I go to the iStore, it says I have already bought the game. The game thinks it is the lite version but I bought the full version back in October.