UDF If based on UDF

[BarefootPaul]

I am trying to create a UDF based on this UDF that I found on the internet somewhere:

Function RefOnPrevSheet(Addr As String) As Variant
    Application.Volatile True
    With Application.Caller.Parent
    If .Index = 1 Then
        RefOnPrevSheet = _
        .Parent.Worksheets(.Parent.Worksheets.Count).Range(Addr).Value
    Else
        RefOnPrevSheet = .Previous.Range(Addr).Value
    End If
    End With
End Function

I have been typing out:
=If(0=RefOnPrevSheet("A1"),"", RefOnPrevSheet("A1"))

I tried writing it as:

Function IfPrevBlank(Addr As String) As Variant
    IfPrevBlank = Application.If(0=RefOnPrevSheet(Addr), "", RefOnPrevSheet(Addr))
End Function

but I get a circular reference error.

Any help is greatly appreciated.