I dont think it was wrong. The fixation was made as per ROPA, 1998 and if you had given option to have the benefit on and from the date of your next increment, it might be fixed on the next December but I think it would not be beneficiary for you. It was better to fix your pay on February.
Now lets see what is written in WBS ROPA, 1998:
(iii) the next increment in the higher post shall fall due after completion of twelve months of qualifying service from the date of refixation of pay .
Therefore, Your date of increment is rightly fixed on February as the same was fallen under the rules of W.B.S. (ROPA), 1998.