Formula Fails to Choose() From Name Range & Results To #Div/0

Hello, can you please help me understand why the formula is resulting in #div/0 & not the desired average even though I have name ranges for each column ? I have the ISERROR Exception for the #Div/0. However, it works if I use a literal hour for the aHours where the Choose() is.

=IF(ISERROR((SUMPRODUCT(--(wekday=CHOOSE(WEEKDAY(B2),"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday")),--(HOUR(wekdate)=CHOOSE(aHours,"23",22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0)),--(Hdcnt)))/SUMPRODUCT((HOUR(wekdate)=CHOOSE(aHours,"23",22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0)*(wekday=CHOOSE(WEEKDAY(B2),"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"))))),"",(SUMPRODUCT(--(wekday=CHOOSE(WEEKDAY(B2),"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday")),--(HOUR(wekdate)=23),--(Hdcnt)))/SUMPRODUCT((HOUR(wekdate)=CHOOSE(aHours,"23",22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0)*(wekday=CHOOSE(WEEKDAY(B2),"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday")))))

Date Day_of_Week Hourly_Hours Headcount
02/20/2010 23:00 Saturday 23 275
02/20/2010 23:00 Saturday 23 300
02/13/2010 23:00 Saturday 23 300