Berkley XML DB strange lock

[wxdqz]

I'm using berkley XMLDB anfd have some trouble using transactions

Using on transaction I do following
TRY_saving a record:
1) Create transaction
2) Read:Try to find an existing record using a Unique name
using the specified transaction
3) if exist modify using existing transaction (succeeds)
if NOT exists create record using putdocument using same transaction (THIS LOCKS ON FOR EVER)


I can only release the lock by using an other transaction for step 2
Can someone explain this ????