Excel #NAME? error

This may seem easy but I've been all over and cannot find an answer. I'm hoping that somone can help. I used a User Defined Function like the one below and get the #NAME? error in the cell. Loaded the Analysis ToolPak - VBA and still no help. Spelling in formula is correct and the function come up with intellisense. any suggestions?

Formula in cell is =Commission(D22) where the value of D22 might be .47

Function Commission(GPM As Double)

Select Case GPM

Case Is > 0.5999

Commission = 0.15

Case Is > 0.5799

Commission = 0.14

Case Is > 0.5599

Commission = 0.13

Case Is > 0.5399

Commission = 0.12

Case Is > 0.5199

Commission = 0.11

Case Is > 0.4999

Commission = 0.1

Case Is > 0.4799

Commission = 0.09

Case Is > 0.4399

Commission = 0.08

Case Is > 0.3999

Commission = 0.07

Case Is > 0.3599

Commission = 0.06

Case Is > 0.3199

Commission = 0.05

Case Is > 0.2799

Commission = 0.04

Case Is > 0.2399

Commission = 0.03

Case Is > 0.1999

Commission = 0.02

Case Is > 0.599

Commission = 0.01

Case Else

Commission = 0

End Select

End Function