Below is a formula I'm attempting to use, and post on my QA Data Sheet Tab.
The actual data is being pulled from my New Rules Client Tab, and while Excel
is accepting the formula in the applicable cell, the outcome value is not
correct (it registers 0, and I know that this is not an accurate outcome).

My requirements are the following:

If a client has completed their class as identified in Column (Y), but has
not yet had their final interview (Column Z), count that total (completed
class, but not had their final interview). I'd appreciate any formula
suggestions to remedy this problem.

Thank You

=SUMPRODUCT('New Rule Clients'!Y4:Y3500="Yes")*(Z4:Z3500="")