Subscriber Cannot Update in Transactional Replication

Hello,

I set up a queued updatable push subscription for transactional replication between two SQL Server 2005 boxes. When the Subscriber updated one of tables, it returned the following error:

Msg 14126, Level 16, State 3, Procedure sp_check_sync_trigger, Line 28
You do not have the required permissions to complete the operation.
Msg 20512, Level 16, State 1, Procedure sp_MSreplraiserror, Line 8
Updateable Subscriptions: Rolling back transaction.
Msg 3609, Level 16, State 1, Procedure <my stored proc>, Line 65
The transaction ended in the trigger. The batch has been aborted.

The account I used is already sysadmin role. Did I miss something else?

Thanks a lot,

Frank