[otrs] Ticket merge gives error, OTRS 2.1.3

Hi, We just upgraded from OTRS 2.0.4 to OTRS 2.1.3 and now Ticket Merge is causing problems. When two tickets are merged, the following happens: 1. OTRS returns a generic "Error" web page, but with no error detail at all 2. the tickets ARE actually merged, BUT all participants receive a merge notification email, even though the "notify user" option is left unchecked. We typically don't want to pester customers with merge notifications, so this has left us unable to use Merge. I've looked through the logs and can't see any error messages. I'd very much appreciate some help in tracking down the cause of this problem, as our team uses ticket merge a lot. Cheers, -Brendan