Getting Prior Year values by selecting curent year variable

Gurus,

My user wanst to see range of data in the report. There is a fiscal year variant wherein user can select Range for fiscal. BUt gives me data only for the range user selected. For eg. User enter 001/2015 to 003/2015. and three months data would be displayed. However, my user wants to see data in the same report for 001/2014  to 003/2014 (prior year same period) I tried to offset it by -12 but then its giving me extra rows with no value. SEe the screen shot below.

Any suggestions how can I achieve this. I am NOT an ABAPER and do not have access to an ABAPER (The person just left company).

Regards

Shirley