AVERAGE calculation

Hello all, 

I would like to ask you for your help with the following situation:

I have the table where I calculate average of filtered productivity by measure "Average":

But when I use the same measure "Average" in gauge I receive totally different number. And I found that the reason is that in the table I am using measure as filter (PO STATUS = "CLOSED") and for the gauge it is not possible. With this filter I am filtering which PO is closed:

When I try to define this filter directly to the "Average" metrics with Calculate formula, I receive this kind of error:

Any idea how to get the proper number to the gauge?

Thanks in advance.

P.