provision for TDS

Hi All

I have posted the goods receipt , and made proivsion for TDS on that . Now invoice posting is done and TDS is posted .

Now I have to do the reversal of the provision made , when I enter the CoCd , fiscal year , and posting date I go to next screen . There I see the invoice no and the cocd along with the reference key.

But the 'save' button is frozen and I am not able to reverse the provision .

If anyone has done that plz explain it to me .