Excel - Pulling data from one selection based on two check boxes (form control)

Cell F17 is to be set at zero, if no data is found in the 3 criteria.

Either Cell E21, G25, or G28 will have the required data.

I need to know how to make F17 (Sheet Count) pull the data if one of the 2 check boxes are checked (G23 or G26) (one or the other, not both) whichever is checked is where the data will pull from, if neither of them are checked, then the data is equal to E11/E21.

Currently I have G23 and E21 working based on if G23 is checked by: E21 "=IF(G23=TRUE,0,4)"

Thank you for your help, I know this may be elementary, but I can't get passed making two check boxes work with another cell with criteria if the other two are not checked.enter image description here