MWST mandatory condition is missing

Hi experts,

Let me explain the scenario first,i have created a contract & saved it here every thing is ok,but when i ma trying to create billing with respect to contract.it is throwing a message "mwst mandatory condition is missing".i have checked the following.

I have gone to condition record and checked it is maintained anyhow if it was not maintained then it won't pick in contract.

checked the teax classification in material master & customer master (it is maintained),gone to pricing analysis and checked what i observed is for mwst condition it is showing "condition record missing" but when i checked in contract for mwst the conditon record is picked (here the record is maintained on country/mat tax classification/cust classification),where as in billing is not picking.may i know where i may went wrong.

Thanks & regards

satish kumar ijju