Hello Swastik,
What date is you costing date? when is the variance calculation date?
One thing i see here is your special period suppose to be 12-16 from Period 2 . As you have special period 4.
so it should be like this in OB52
period 1- 1-12 and then period 2- 12-16
you're using a fiscal year variant that is "year-dependent" and thus you have to maintain this customizing every year in OB29 check if it is maintained.
Thanks
Hrusikesh