Help plz....

Go to voucher to which you want to change the date. Press Alt + F2 and give Period 01/04/2012 to 31/03/2013. Than change the date of voucher to 07/08/2012.

even after trying this it was showing error .. 

Is Tally you are using is License Version?

Please change date of your computer system to 07/08/2012 and then foolow the guidance of Dimple Thacker.. Hope this will do!

even it is only accepting 31-3-2012 if any other date like 1st of any month or other it was showing  error date below starting of books

Change period to 1/4/2012 to 31/3/2013. & try

i got that another doubt 

how entries for advance adjusted against payment afterwards including discount received  to be made in tally