Hiky

You could have hidden fileds beside the from fields and unhide them to display a error message using javascript when the from is submitted.

*-The html / asp part -* <asp:DropDownList ID="DropDownList" onchanged="enableTextBox();" runat="server"> <asp:ListItem Text="" ></asp:ListItem> <asp:ListItem Text="Yes" ></asp:ListItem> <asp:ListItem Text="No" ></asp:ListItem> <asp:DropDownList> <asp:TextBox ID="TextBox" Enabled="false"></asp:TextBox> *-the javascript part-* function enableTextBox() { if(document.getElementById("DropDownList").value == "Yes") { TextBox.disabled == false; } }