feel free to send me ftp info and admin login and I can test.
The only way to recieve that message would be if the ad can not be found like say if someone clicked an email link for an ad that is already deleted from the system that is possible.
Otherwise if you as admin hit the sold link on an active ad and then refresh and hit the resell you should see this action works. If you still have an issue feel free to send me info through the contact us link and I will take a look.