how to fire check text change event in asp;net

----------source page
<asp:TextBox ID="TextBox1" runat="server" ontextchanged="TextBox1_TextChanged"></asp:TextBox>

.cs page------------
protected void TextBox1_TextChanged(object sender, EventArgs e)
{
Response.Write(TextBox1.Text.Trim());
}
nothing happening on this code --------then what is textchange event
if we write something in txtbox then edit this is txtchange event or something else