Sub blabla()
    Dim db As DAO.database
    Dim obj As Object
    Set db = CurrentDb
    Const conPropNotFoundError = 3270
 
    On Error GoTo ErrorHandler
    db.Properties!AppTitle = "DeinTitel"
    Application.RefreshTitleBar
Exit Sub
 
ErrorHandler:
    If Err.Number = conPropNotFoundError Then
        Set obj = db.CreateProperty("AppTitle", dbText, "DeinTitel")
        db.Properties.Append obj
    Else
        MsgBox "Error: " & Err.Number & vbCrLf & Err.Description
    End If
    Resume Next 
End Sub