how to get the last period balance into current period balance in webi

Hi All,

i am want to show last month  balance  values in current month, my requriment is

if User is select the fiscalyear period in promt like 2014 jan to 2014 aug

report should be like this  for every month

if fiscal year period is jan 2014 then Balance Inventory value should be the value of dec 2014 Balance Inventory

Thanks

Sreeni