how to clear the textbox

Hi,

I am new to asp.net.and this question seems pretty silly, but I really can't figure out what is wrong.

I am having an issue with clearing the textbox.
I tried textbox.text=string.empty, textbox.text="" but none of these seem to help, the textbox just doesn't get cleared.

Can someone tell me if I have set something in the code that's not allowing me to clear the textbox?

[Edit: added code snippet from comments below - Henry]

<asp:TextBox ID="TextBox3" runat="server" Width="177px" ontextchanged="TextBox3_TextChanged" Height="16px" style="margin-left: 5px"></asp:TextBox> 

protected void Button11_Click(object sender, EventArgs e)
{
  Panel1.Visible = false; DropDownList5.ClearSelection();
  TextBox3.Text = string.Empty;
}

[/Edit]

Tags: ASP.NET