This is a bit of a weird one: I'm using a custom child theme and I have WP E-Commerce set up on my site to sell my music (I have a record label) and I'm getting an error with PayPal but only when I'm using my child theme.
When I'm using my child theme, when someone goes to checkout they are then routed to PayPal Express Checkout to complete their transaction. Upon clicking the 'Make Purchase' button, I get an error which states that the version of PayPal Express Checkout is incorrect.
I called PayPal merchant services and what's weird is that the PayPal gateway version number the shopping cart is sending is 0.9.6.1 (!!!???) I thought, wait, this number looks familiar and it is the version number of Thematic. What's even weirder is that if i use another theme, the transaction goes through without the error. It even works when I'm using just Thematic!
I'm kind of at a loss here as to why the Thematic version number is being sent with the API call to PayPal. Maybe if someone knows where this number is stored and then I can try to troubleshoot from there.