Pls help - Need to fix formula with Spill Error

Hello! I am struggling to get a formula to work. I have looks in my notes, Youtube, and Google and the best I get is a #SPILL! error...

I am making a workbook for work.

On Sheet1 I need a single cell formula to show the single value total of all blank cells in Column B of Sheet2, but only if there's a value in Column A of sheet2 in the same row.

The closest I've gotten, though it shows the spill error is:

=FILTER(Sheet2!B1-B1000, (Sheet2!A1:A1000 <> "") * (Sheet2!B1:B1000 = ""))

I got it from Googling, but it is close to what I attempted to write myself, but excel just breaks when I tried to solo write it lol

If anyone with any degree of skill could help, that'd be so very swell.