Conditional summing across multiple sheets

Hi,

I am trying to sum the same cell across multiple sheets, but want to incorporate a summing criteria. Ordinarily I would use '1:3'!C23 (for example) to sum the same cell (C23) across sheets 1 to 3.

However, say C23 on sheet 2 doesn't fit my criteria (such as cell C1 on all sheets being the name of a client), yet C23 on sheets 1 and 3 do - is it possible to use this type of formula and incorporate a criteria such that the result would be sum('1'!C23,'3'!C23)?

So, this is the formula I came up with after reading multiple threads:

=SUMPRODUCT(SUMIF(INDIRECT("`"&PropertyList&"`!$A$2"),"Crestline",INDIRECT("`"&PropertyList&"`!C12")))

And then updated to

=SUMPRODUCT(SUMIF(INDIRECT("`"&PropertyList1&"`!$A$2"),"Crestline",INDIRECT("`"&PropertyList1&CELL("address",C12))))

After all that work, I still get #ref error.... I went to "evaluate formula" and it seems to work fine until -INDIRECT("`"&PropertyList1&"`!$A$2")- this part shows #ref at the end of the step.

Do you guys see anything odd or wrong in the formula?

Please let me know.
Thank you in advance.
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That worked!!!!! Thank you so much guys!!!!
Another question!
IF I want to make this two or more criteria instead of meeting one criteria, how should I modify the formula?