#NAME? error in Excel for VBA Function

I am making my first VBA program and trying to run the following function. The function checks a specific named range for the first row which does not have a value greater than it's leading value, but less than 1.

Public Function findPurchase()Dim CRT As RangeSet CRT = Range("CostRateTable")Dim existsBetter As BooleanexistsBetter = TrueDim r As Integerr = 2Dim c As Integerc = 4While existsBetter    Dim Found As Boolean    FoundBetter = False    While Not FoundBetter And c <= CRT.Columns.Count        If CRT(r, c) > CRT(r, 2) And CRT(r, c) < 1 Then            FoundBetter = True        Else            c = c + 1        End If    Wend    existsBetter = FoundBetter    If existsBetter Then        r = r + 1    End IfWendfindPurchase = CRT(r, 3)'MsgBox(findPurchase)End Function

I know the function does what it is supposed to because I have both manually checked the table of values, removed the comment ' from the MsgBox, and used the debug tools to step in and out of each of the functions steps as it went through the table. However, when I reference the function in Excel with =findPurchase() I'm given a #NAME? error. The function even shows up in the function auto-complete box when I begin to type its name. When I write other functions, both with and without parameters, I can reference them just fine, for example:

Function addtwo()    addtwo = 1 + 2End Function

What am I doing wrong with my function which causes it not to work?