SUM two fields on two sheets based on a lookup across sheets?

I am sure this is basic and I am just missing something stupid but:

I have the following:

Sheet1 Field A | Field B | Field C Name | Title | Percentage Sheet2 Field A | Field B | Field C Name | Age | Percentage (calculated in a formula) 

On Sheet 3 I need to find the matches across the sheets and then SUM the percentages in Field C.

I thought I could do this with:

=SUM(XLOOKUP(Sheet1!A1, Sheet2!A:A, Sheet2!C:C, 0, 0):XLOOKUP(Sheet1A1,Sheet1A:A,Sheet1C:C,0,0)) 

When I run this though I get an !VALUE error but evaluating the error doesn't give any indication of what is wrong. The only thing that I think could cause the issue is that Field C in Sheet2 is calculated and that formula is actually being pulled in as the array.

Any other ideas on what could cause the issue? Is there a better way to do what I am describing?