[RESOLVED] My Public Function only works in a worksheet cel. Versions conflict!

[Tobian]

When I insert following Public Function ValueOneBack() in a Cell of a Excel worksheet, it works.
Eg. when I insert ValueOneBack() in Cell H7, it returns the value of Cell G8.

Now I want to know if the result of ValueOneBack() is also present in Range B1:B4. So I use the result of ValueOneBack() as LookupValue in the Function MatchOneBack(). But now ValueOneBack() doesn't return a value, which makes MatchOneBack() always false.
Can somebody tell me what I do wrong?

Public Function ValueOneBack() As Variant
    
    ValueOneBack = ""
    
    Application.Volatile
    
    If TypeName(Application.Caller) = "Range" Then
        If Application.Caller.Row <> 65536 And Application.Caller.Column <> 1 Then
            ValueOneBack = Application.Caller.Offset(1, -1).Value
        End If
    End If
 
End Function
 
Function MatchOneBack() As Integer
    Dim LookupValue As Variant
    Dim rngMatrix As Range
    
    LookupValue = ValueOneBack
    
    Set rngMatrix = Worksheets(1).Range("B1:B4")
        
    If rngMatrix.Find(What:=LookupValue, _
                        LookIn:=xlValues, _
                        LookAt:=xlWhole, _
                        MatchCase:=False) Is Nothing Then
        MatchOneBack = 0
    Else
        MatchOneBack = 2
    End If
        
    Set rngMatrix = Nothing
    
End Function