Hi to all,

I want to have a userdefined function which accepts a range over more
then one sheet.
eg: MyFunction(Sheet1:Sheet3!A1:B10)

This is code

Public Function MyFunction(ByVal MyArea As ????) As Long
Dim rngCell As Range
Dim lngResult As Long
'
Application.Volatile
'
On Local Error GoTo MyFunction_err

For Each rngCell In MyArea
' Do this and that to calculate lngResult
Next rngCel

MyFunction = lngResult
GoTo CountUniqueValues_exit
CountUniqueValues_err:
MsgBox Err.Description, , Err.Number
MyFunction = -1
CountUniqueValues_exit:
Set UniqueValues = Nothing
End Function

With the standard function SUM you can do this.

I have tried these definitions:
MyFunction(ByVal MyArea As Range) = #VALUE
MyFunction(ByVal MyArea As Variant) = Error 424 / Error 2015 on
MyArea
MyFunction(ByVal MyArea As Object) = #VALUE

Any ideas?