I used Microsoft.SharePoint.Client.ListItem still I am getting error.

I am getting error at foreach loop when i am using Listitem . the error says there is a ambiguity between system.data and microsoft.sharepoint

protected void chkboxIncentive_SelectedIndexChanged(object sender, EventArgs e) { foreach (ListItem checkbox in chkboxIncentive.Items) { //If this particular item is checked if (checkbox.selected) { checkbox.Text = String.Format("{0}<input id=\"TextBox{0}\" name=\"TextBox{0}\" / >", checkbox.Value); //TextBox tb = new TextBox { ID = checkbox.Value }; //Input.Controls.Add(tb); } } } its throwing error at ListItem saying ambiguity and another error at selected and value

I have a custom input form some of the fields are coming from a list in SharePoint 2010. I have a check box control which is populated by a list item. there are around 10 rows. Now i want when a user select a check box list item, a text box should appear beside it. for example I have a list called subjects, which have column name title and the entries are physics, maths, chem etc... Now when a user select physics from the check box list a text-box should appear beside it and user should be able to write on text box.