[otrs] Ticket merge error

Hi, When I try to merge a ticket, I get an error like this: Can't call method "LockSet" on an undefined value at /opt/otrs//Kernel/System/Ticket.pm line 3720, <PRODUCT> line 224. Does anyone have a clue what this is? Leah -- Leah Cunningham : d416-585-9971x692 : d416-703-5977 : m416-559-6511 Frauerpower! Co. : www.frauerpower.com : Toronto, ON Canada