Fejl ved Try Catch

Jeg får en fejl ved min Try / Catch funktion

        Try

            Dim SQLCon As String = ConfigurationManager.AppSettings["OpenCalender"]
            Dim query As String = "INSERT INTO Aktivitet (Dato, Bemaerkning) VALUES ('" & TextBox1.Text & "', '" & TextBox2.Text & "')"

            Dim MyCon As SqlConnection = New SqlConnection(SQLCon)
            MyCon.Open()

            Dim cmd As SqlCommand = New SqlCommand(query, MyCon)
            Dim rd As SqlDataReader = cmd.ExecuteReader()

            rd.Close()
            MyCon.Close()

        Catch ex As Exception

            MsgBox(ex.Message)

        End Try

Jeg får at vide: "SQLCon is not declared"

Hvad kan det skyldes ?