I'm posting this because I just lost a couple of hours trying to figure it out.
I'm using HikaShop Business 1.4.5 on Joomla! 1.5.22
Every payment that went through was being marked as "unclaimed" on the purchaser's paypal account without any notification on the seller's paypal account.
In order to fix this, check the e-mail address in the Paypal plugin configuration page. The e-mail address must be all lower case or the orders will be marked as unclaimed.
I hope this helps anyone who runs into the same problem.
Ben Inkster
Geek Incorporated
