Sum display the result of an IF formula

I'm trying to sum out services on an excel build sheet I have. I need to add a 8 dollar fee if a monitor is sold. right now i have =IF(E16>N13, "8.00",IF(E16=0,E16))

this formula displays the information in the needed location however another formula that refers to the location the provided formula is will not include the result of the formula in its sum total

so for an example:

if E16 = $200

then E28 {which contains the =IF(E16>N13, "8.00",IF(E16=0,E16))} = $8

the D33 {which contains =sum(e26:28)} since E26:27 are blank D33 should show = $8

but D33 will not populate whats in E28

Please show me what I'm missing