Saving Documents on BLOB columns

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Please, help me with this:

I created a new table:
CREATE TABLE testfile
(file blob);

and created a new Form with Ole Container Item to save document on Database.

I can insert new Word Document and edit this doing double click on the container, but, when save (commit) record on the database, I can't edit again the Word document, becuase Forms show next error:

FRM-40501: ORACLE error: unable to reserve record for update or delete

I checked all Block and Item Properties and all is Ok
Insert Allowed = Yes
Update Allowed = Yes
Delete Allowed = Yes
Locking Mode = Automatic
Key Mode = Automatic

I'm using Oracle8i Enterprise Edition Release 8.1.7.3.0
and forms 6i (Version 6.0.8.8.0)

Thanks for you help