Marketpress Cubepoints Integration

I'm Using Cubepoints, Along With Marketpress...on the marketpress side, it works great! however, I have my paypal setup with PDT and IPN setup to work with cubepoints.. however, when a person purchases points, they are not credited in their accounts with a multitude of the points they purchased... the problem with this is obvious.. im wondering why it wouldnt update though? could it be a PHP error? my host 1and1 uses php version 5.2.17... obviously wordpress recommends a minimum of 5.2.4.. however i didnt notice that until after i had purchased my package with 1and1.. is this the issue at all? and is there a more suitable hosting solution for me that offers more compatibility with wordpress if this is the case? i would like to use cubepoints.. i hae many features built into my website that take advantage of them.. and the fact that marketpress (which i also use adamantly) is integrated with it makes it all the better... any suggestions on how to fix this problem? please advise