xsi5 : unexpected error in SAVE DEFORM KEY

Hey guys, just curious if any one else has had difficulty with this little tool. I can't seem to save any deform keys using the "Link Deform with Orientation" tool. Every time I select the the cluster, a go SHAPE> DEFORM KEYS> SAVE DEFORM KEY I get an "unexpected error" message. I can't seem to find a way around it.

ANy Ideas? Thanks in advance.