How can I not allow the form to go through if the user selects "other" from the DDL and not enter in something in the textbox to describe other:
How did you hear about us:
<asp:RadioButtonList ID="RadionButtonList1" runat="server">
<asp:ListItem>Newpaper Ad</asp:ListItem>
<asp:ListItem>Radio</asp:ListItem>
<asp:ListItem>Other</asp:ListItem>
</asp:RadioButtonList>
<br />
<br />
<asp:TextBox ID="textbox1" runat="server"></asp:TextBox>
<asp:Button ID="Button2" runat="server" Text="Click" />
How did you hear about us:
<asp:RadioButtonList ID="RadionButtonList1" runat="server">
<asp:ListItem>Newpaper Ad</asp:ListItem>
<asp:ListItem>Radio</asp:ListItem>
<asp:ListItem>Other</asp:ListItem>
</asp:RadioButtonList>
<br />
<br />
<asp:TextBox ID="textbox1" runat="server"></asp:TextBox>
<asp:Button ID="Button2" runat="server" Text="Click" />