Andy,

Null is a special subtype of Variant type variables. An empty
string is NOT a null. IsNull tests only Variant type variables.
To test for an empty string, use code like

If S = "" Then
' or
If Len(S) = 0 Then


--
Cordially,
Chip Pearson
Microsoft MVP - Excel
Pearson Software Consulting, LLC
www.cpearson.com



"Andy" wrote in message
...
Hi,
I am trying to create a function to deal with nulls, but I'm
enconntering an
error (invalid use of null) by simply passing null to a
function.

The following code creates the issue

Sub go()
Dim sreturn As String
sreturn = nulls("hello")
MsgBox "return is :" & sreturn

sreturn = nulls(Null)
MsgBox "return is :" & sreturn
End Sub

Function nulls(instring As String) As String
If IsNull(instring) Then
nulls = ""
Else
nulls = instring
End If
End Function

Does anybody have any ideas?

Many thanks in advance
Andy