I've got an equation built in my global variables that determines the type of drawer glide I'm using in a cabinet. The equation I've built works in excel when I replace the global variable name with a cell location, but when I change the names back and pop it into solidworks, it doesn't work?

IIF ( "Hole C" = 20 , 10 + 5 / 8 , IIF ( "Hole C" = 12 + 13 / 16, 13.75 , IIF ( "Hole C" = 14.0625 , 15.75 , IIF ( "Hole D" = 25 , 17 + 11 / 16 , IIF ( "Hole D" = 17 + 13 / 16 , 19 + 11 / 16 , 21 + 5 / 8 ) ) ) ) )

The hole placement that is determined by the depth of the cabinet should then drive the profile length of the slides. 

When I enter the values of C = 15 3/16 and D = 17 13/16, it outputs 13 3/4, so I feel like it's getting hung up in the second if statement, but I can't figure out why?