my function is giving value error

Hey whenever I try and run this simple function it give me a value! error and have no clue why? What im trying to do is if VA isnt either VOLUME OR SURFACE AREA and SH isnt either PYRAMID OR PRISM then PyramidPrism is "Invalid Object" else it is just 1 for now.

Public Function PyramidPrism(ByVal length As Double, ByVal width As Double, ByVal height As Double, ByVal volumearea As String, ByVal shape As String) As Variant
Dim VA, SH As String

VA = UCase(volumearea)
SH = UCase(shape)

If VA <> "VOLUME" And VA <> "SURFACE AREA" And SH <> "PYRAMID" And SH <> "PRISM" Then
PyramidPrism = "Invalid Object"
Else
PyramidPrism = 1
End If


End Function