Member not upgrading after payment

Done a few "Sandbox" test payments and the membership level doesn't get updated. I have selected "IPN" on payment setting, could the issue be that since it's a "sandbox" test transaction, the script doesn't upgrade the membership?

it works fine

read this it might help you

http://www.boonex.com/unity/forums/#topic/Paypal-and-Membership-Levels.htm

Thanks, it helped, although I'm having other issues after payment now, but that's another issue...Thanks...