Count blanks with criteria

[jjrrcc11]

Hello

I wish to count blank cells, presumably using =COUNTBLANK but I wish to only count the blanks prior to the final column with a value in.

So for example

Row 2's last value is in column AO, so I wish to count the number of blanks between A and AO... despite there being further blanks after AO... I do not wish for these to be included.
Row 3's last value is in AE... so similarly I only wish for the blanks prior to AE to be counted.

This is a 2000+ row spreadsheet and each row may have a different last value point...

Thanks in advance

 

[jjrrcc11]

Starting in column Z you will need to change the 2:2 to Z2:CW2, 2:2 was a method to use the whole row, I think the -1 will still hold true at the end of the formula

Thanks. Unfortunately I just seem to get a count of 0?

 

[jjrrcc11]

Anyone have any ideas? thanks