从xml文件读取值并绑定多个控件，控件互相干扰的问题 求助
大家好  我写了个函数用来从xml文件中读取控件的值，然后绑定。但是奇怪的是，当选择控件comboBoxEx41的值时， comboBoxEx42和comboBoxEx43 也同时变成和 comboBoxEx41 一样了。  请问是什么问题呢？
我想让三个控件绑定相同的属性值，操作互不干扰，应该怎么修改呢？ 谢谢  下面是代码：

//从xml文件中绑定控件

            private void update1()

        {

            DataSet ds = new DataSet();            

            string fromPath = System.Environment.CurrentDirectory + @"\conf\rate_group.xml";

            FileInfo xmlFile = new FileInfo(fromPath);

            if (xmlFile.Exists)

            {

                FileStream fsReadxml = new FileStream(fromPath, FileMode.Open);

                XmlTextReader myXmlReader = new XmlTextReader(fsReadxml);

                ds.ReadXml(myXmlReader);                

                myXmlReader.Close();

            } 



            comboBoxEx41.DataSource = ds.Tables[0];

            comboBoxEx41.DisplayMember = "displaymember";

            comboBoxEx41.ValueMember = "valuemember";

            comboBoxEx41.SelectedIndex = -1;

            comboBoxEx41.DropDownStyle = ComboBoxStyle.DropDownList;





            comboBoxEx42.DataSource = ds.Tables[0];

            comboBoxEx42.DisplayMember = "displaymember";

            comboBoxEx42.ValueMember = "valuemember";

            comboBoxEx42.SelectedIndex = -1;

            comboBoxEx42.DropDownStyle = ComboBoxStyle.DropDownList;





            comboBoxEx43.DataSource = ds.Tables[0];

            comboBoxEx43.DisplayMember = "displaymember";

            comboBoxEx43.ValueMember = "valuemember";

            comboBoxEx43.SelectedIndex = -1;

            comboBoxEx43.DropDownStyle = ComboBoxStyle.DropDow