The password used to open up the database does not give you write access to
all fields.  Your program has used DBGET to retrieve a record, then modify
an item (for which the password says you can view), and then DBUPDATE was
called to update the entry (perhaps with @; as the item list).

Correct problem by:

1.  Using different password OR
2.     fix program logic not to modify the read only field in the programs
copy of the data OR
3.     change program to use a list only the fields that truly need to be
updated.