Enabling RequiredFieldValidator From Code Behind

Question

I'm displaying an error message for the requiredfieldvalidator from code behind but the display is set to none or visible is hidden. I tried to do .visible = true but it's still hidden. How can I make it to show the error message? The textbox is inside a GridView.

<asp:TemplateField HeaderText="SSN">
    <ItemTemplate>
    <asp:TextBox ID="txtSSN" runat="server"></asp:TextBox>
    <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="txtSSN" />
     </ItemTemplate>
</asp:TemplateField>

TextBox txtSSN = (TextBox)r.FindControl("txtSSN");
if (txtSSN.Text == "")
        {
      RequiredFieldValidator RequiredFieldValidator1 = (RequiredFieldValidator)r.FindControl("RequiredFieldValidator1");
      RequiredFieldValidator1.Visible = true;
      RequiredFieldValidator1.Enabled = true;
      RequiredFieldValidator1.ErrorMessage = "This field is required.";
        }

Answer 1

Set the IsValid property to false.

RequiredFieldValidator1.IsValid = false;

You shouldn't need to bother with the visibility, this will happen automatically.