@prior not executing as expected

Summary:

@prior not executing as expected, need to get the value 12 months back from the current month which im calculating.

Content (required):

Hi

Im using @prior to get the value before 12 months from the current period/month. Following is my rule.

when i launch this no value appears for me, even though there are values 12 months back in the system.

Please help.

"OFS_Calculated"

(

IF("Calculation Basis"->"BegBalance"->"No Year"->"Total Product"->"All Branch"==1)

"OFS_Calculated" = /*("Load Total"->&LastYr1->"OEP_Actual"-> "Working_PTD"->&LastPer1);*/

(@prior("Load Total"->"OEP_Actual"-> "Working_PTD",12,@xrange(&Lastyr1->&Lastper1,&Lastyr12->&Lastper12)));