"ByRef argument type mismatch error" trying to use my first UDF

I am stuck,

I am only marginally familiar with arrays and I can not figure out how to deal with the "ByRef argument type mismatch error" the Sub gives because "Area" is a variant not a string

Thanks

Sub Area()
    Dim Areas As Variant
    Dim Area As Variant

    Areas = Array("K2:K", "R2:R", "Y2:Y", "AG2:AG")

    For Each Area In Areas
        If Not DoIHaveARange("XXX", Area, "Yes") Is Nothing Then 'Code
    Next Area

End Sub

Public Function DoIHaveARange(ShtName As String, Rng As String, FindWhat As String) As Range
Dim ws As Worksheet
Dim lRow As Long

 Set ws = ThisWorkbook.Sheets(ShtName)
  lRow = ws.Range("A" & ws.Rows.Count).End(xlUp).Row

   Set DoIHaveARange = Range(Rng & lRow).Find(What:=FindWhat, LookIn:=xlFormulas, _
                 LookAt:=xlWhole, SearchOrder:=xlByRows, SearchDirection:=xlNext, MatchCase:= _
                 False, SearchFormat:=False)
End Function