We are trying to use lockSQL property to get header lock when the
user accesses the lines on a master-detail relationship.
We wrote the sql property in the following way:
UPDATE MYTABLE SET
MYCOL1 = MYCOL1
WHERE MYKEY = :OLD_MYKEY

as indicated in IBO help, but we get a DML error:
Invalid custom DML reference column OLD_MYKEY

We have checked several times the sentence syntax and, of course,
MYKEY exists and belongs to MYTABLE.

Any help will be wellcome, thanks in advance.
Manel