Invoice values has become to zero after updating

Hi

we have one down payment request which was created with reference to contract and it had pricing error and after analyzing the error we came to know that tax condition was missing because of missing condition records, so we have maintained condition records and clicked on update tab in VF02 tax condition was picked but the pricing conditions has turned to 0.

when we again go to VF02 we see that all the tabs are greyed out and we were not able to change the invoice now and no further succeeding document has been created to it

now i want the invoice to be at its original price,

so need inputs on this

Thanks

Naveen