tds on down payment

Hi every one

                 while making a down payment to vendor using t-code f-48, am getting below error (the error is not in red colour it's green only,and system not calculating tds on down payment whereas invoice it will be calculatd without errors)

pricing error: mandatory condition 29OT is missing.

29ot is out put tax condition type, why the system is throwing pricing error am doing down payment go vendor.....I don't know what the reason behind to throw pricing error.

could anyone  throw some points to solve an issue.

regards

Raj