Microsoft Excel Formula that will not calculate

Hello, I’m building an excel spreadsheet to study how coupons are being redeemed and how they affect revenue . The excel formula I’ve been using is: {=SUM(IF(‘ENTER INFO HERE’!$F$4:$F$15000=”T9E”,IF(‘ENTER INFO HERE’!$G$4:$G$15000=”F125″,’ENTER INFO HERE’!$C$4:$C$15000,0),0))}. Now I realize “F125” may conflict with a cell reference in excel, however, I have other codes that are similar to this one and they are calculating. My question is, how come this formula in particular is not calculating, while others will?