HP ALM 12 with TDAdmin API

I use TDAdmin user to connect with HP ALM 12 through TD/OTA API and when I try to update the LOCK
table , I get below error message.

Invoke of Execute
You do not have the required permissions to execute this action.

Say for example query is

UPDATE LOCKS SET LK_OBJECT_KEY='-75' WHERE LK_OBJECT_KEY='74' AND LK_OBJECT_TYPE='BUG'

The same update query works fine for the same user when updated through web interface (site
admin mode). I tried using delete query for the same table through TDAdmin API with the
same TDAdmin user and Iam able to delete the entry from the Lock table successfully.

So Its just update to the lock table is not working for the TDAdmin user through TDAdmin
api.

Also the same update/delete query works fine with HP ALM 11 for the same user.

I would like to know whether any recent changes on HP ALM 12/TDAdmin API on this regard.

Thanks