"Sumif()" in Calc not working

Calaculation “=SUMIF($C$3:$C$46,“Yes”,I$3:I$46)” does not work in a new spreadsheet, but worked ok in last year’s copy.

if I try “=SUMIF(F31:F36,“SO”,G31:G36)” then that works ok.

LibreOffice version: running under Mac OS 10.6

And “does not work” exactly means what?

It returns a zero value

Maybe you are comparing “Yes” as text with cell with 0 for false other number for true. Please what is the value in a cell with Yes (Not the format).