BlueSky.Windows.ValueLablesDialog.valLblChangeBut_Click C# (CSharp) Method

        private void valLblChangeBut_Click(object sender, RoutedEventArgs e)
        {
            if (ValLstBox.SelectedIndex >= 0)
            {
                int index = ValLstBox.SelectedIndex;
                ///////add////////
                //string newv = ValuetextBox.Text;
                string newl = labelTextbox.Text;

                //validations here. 1.No duplicates, 2.v could be numeric only
                //Checking duplicate value and lable
                if (isDuplicate(newl))
                {
                    MessageBox.Show("Duplicate entry!");
                }
                else
                {
                    vlmatrix.changeLevel(ValLstBox.Items.GetItemAt(index).ToString(), newl);//shud com first, before changing valLstBox itms.
                    /////remove////////
                    ValLstBox.Items.RemoveAt(index);
                    //Adding to list if value is unique
                    ValLstBox.Items.Insert(index, newl);
                    
                    //ValuetextBox.Text = "";
                    labelTextbox.Text = "";
                    modified = true; 
                }
            }
        }