Revisit: Summing with date difference and conditions

[ZedaG]

A month ago, Pete_UK solved a problem for me with this formula:

=SUMPRODUCT((DATEDIF($B$2:$B$16,C$2:C$16,"m")>=$H2)*(DATEDIF($B$2:$B$16,C$2:C$16,"m")<$I2))

The original problem was that I wanted to use a formula that will sum the date difference between each of the date columns and Client DOB by condition and put that information into tables. For example, I want to sum groups of "date diff" between client DOB and Client Intake by age categories by month:
16-19 months
20-25 months
26-30 months
and so on.

The original solution worked fine for me until I have missing dates (formula turns to #num!). I tried various things, but nothing worked. I’ve attached the file. Is there a way to calculate this with missing dates?

Thanks again

Zeda

[CK76]

Try...
=SUMPRODUCT((IFERROR(DATEDIF($B$2:$B$16,C$2:C$16,"m")>=$H2,0))*(IFERROR(DATEDIF($B$2:$B$16,C$2:C$16,"m")<$I2,0)))

Confirmed as array (CTRL+SHIFT+ENTER).

[ZedaG]

Worked beautifully. Thanks so much.

Tamra