Textbox inside the Gridview doesnt raise an event

<div>
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
        DataSourceID="SqlDataSource1">
        <Columns>
            <asp:TemplateField>
                <ItemTemplate>
                    <asp:TextBox ID="TextBox1" runat="server" AutoPostBack="True"
                        Text="<%# Bind('orderID') %>" ontextchanged="TextBox1_TextChanged"></asp:TextBox>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField>
                <ItemTemplate>
                    <asp:TextBox ID="TextBox2" runat="server" Text="<%# Bind('productID') %>"></asp:TextBox>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>
    <asp:SqlDataSource ID="SqlDataSource1" runat="server"
        ConnectionString="<%$ ConnectionStrings:testConnectionString %>"
        SelectCommand="SELECT [orderID], [productID] FROM [ODetails]">
    </asp:SqlDataSource>
</div>

protected void TextBox1_TextChanged(object sender, EventArgs e)
{
    Response.Write("<script> alert('test')</script>");
}