Formula lookup with a return of 0 if not found, using that return in an adjacent cell

Hello,

I appreciate any help figuring this issue I am having with a formula out.

In cell AA15 I have the formula:
=XLOOKUP(Z15,$B$14:$B$400,$I$14:$I$400,"0")

The value returned is 0

In cell AB15 I have the formula:
=IF(AA15=0,SUM(AB14+1),0)

The response I am looking for is 1, but it is returning 0.

It should be summing AB14 which is 0 plus 1, but I think the error lies in the formula in AA15.

Although AA15 is returning 0, I think it doesn't recognize the cell as having a value of 0.

I appreciate any help with this.

Thank you,
Nick

Sorry, found the issue, I had " " around the first 0