According to ApniTally ReaderMahender Rana from Rajkot, if we credit salary to employee A, B and C for Rs. 1500, 1700 and Rs. 2000 on 31st Jan, 2008 and later try to modify the voucher, it would not accept. Tally would not show the employee under primary cost category and courser wouldn't move. For example if have to do deductions for employee A say for Rs100/- then voucher alteration is not possible while going to voucher via Display -> Account Books-> Ledger Account -> Salary payable.
This problem can be overcome by altering the date of joining of the employee below 1/4/2007. Dates above this date would not work. However the joining date of the employee can be altered again after doing the modifications in voucher.