Including a Range in Formula, Less a Cell

I have a formula with a range specified and it spans a series of cells in a column that is broken in the middle by a single cell (this cell contains text which is just there to aid the entering of information aka. a column header). If i include this text cell in the formula, it comes back blank. If I skip it in the range, it comes back blank.

Here is the formula;

=IFERROR(SUMPRODUCT(($E$51:$E$81<=165.1)*($M$51:$M$81)),"") - this works fine but does not include the entire range I want

I tried something simple like;

=IFERROR(SUMPRODUCT(($E$51:$E$81,$E$83:$E$92<=165.1)*($M$51:$M$81,$M$83:$M$92)),"") - this comes back blank

Added section bolded.

As you can see I am just trying to add a second range within the same function while skipping one header cell mid-range.

Unfortunately no. It is still coming back blank. I am wondering if there is any way to ignore the header cell...

Also what are the hyphens for/do?

Very good! Works well. Thank you very much.