=SUMIF($A$9:$A48,"<=16",D$9:D$48)

The above works.

But what I need to do is to have the "<=16" get the variable value 16 from a
cell. The cell address with the current value 16 is AH1 and is on the same
worksheet.

Sorry folks - I can't figure out how to do this. If I enter "<=16", I get
the correct value. If I enter "<=AH1", I get 0.