12 Month Avg & Total Calc both Income Statement & Balance Sheet Accounts

Need 2 difference calcs:  one for Balance Sheet & Income Statement

Calc for a 12 Month Rolling Avg using MDX Function in ASO Cube

Case when (IsLeaf([Month].currentmember) and not (IsEmpty([Month].currentmember))) then
AVG (
{TUPLERANGE(
   ([Fyear].currentmember.lag(1), [Month].currentmember.NextMember), ([FYear].currentmember.lag(1), [Dec])),
  TUPLERANGE(
    ([FYear].currentmember, [Jan]), ([FYear].currentmember, [Month].currentmember))})
Else
   Missing
END

However this DOES NOT Work if the 12th month has a zero balance.   The calc brings back a zero

Same happens for the 12 Month Rolling Total (Want the total for the past 12 months)  here is that MDX Function from the ASO Cube

Case when (IsLeaf([Month].currentmember) and not (IsEmpty([Month].currentmember))) then