Dim t As TextBox = Nothing
        Dim cb_min As ComboBox = Nothing
        Dim cb_max As ComboBox = Nothing
        Dim zw, zwmin, zwmax As String
        Dim c, cc As Control
        For i As Integer = 1 To 10
            zw = "TXT_0" & i.ToString
            If i = 10 Then zw = "TXT_" & i.ToString
            For Each c In GB_eingabe.Controls
                If TypeOf c Is TextBox And c.Name = zw Then
                    t = CType(c, TextBox)
                End If
            Next
            For Each cc In GB_MM.Controls
                zwmin = "CB_0" & i & "_MIN"
                zwmax = "CB_0" & i & "_MAX"
                If TypeOf cc Is ComboBox Then
                    If cc.Name = zwmin Then
                        cb_min = CType(cc, ComboBox)
                    End If
                    If cc.Name = zwmax Then
                        cb_max = CType(cc, ComboBox)
                    End If
                End If
            Next
            If t.Text.Length < cb_min.SelectedItem Then
                MsgBox("Feld zu kurz")
                t.BackColor = Color.Red
                fel = True
                t.Focus()
            ElseIf t.Text.Length > cb_max.SelectedItem Then
                MsgBox("Feld zu Lang")
                t.BackColor = Color.Red
                fel = True
                t.Focus()
            Else
                t.BackColor = Color.White
            End If
        Next