Series problem with monthly average

[ski_jr23]

This is my formula works great except I would like to exclude months that are at zero so the running average isn't so low?
When I tried adding ">0" it doesn't like that added in to the formula and countif statement it doesn't seem to like it in this series formula.
=SERIES('2012'!$M$8,('2012'!$N$7:$Y$7,'2012'!$AA$7),('2012'!$N$8:$Y$8,'2012'!$AA$8),1)