Help On Events firing to bind data

Hi
I have placed a drop down by the side of it i placed a go button by side of drop down ,based on value selected in drop down i am binding values to a grid view .
Here i am writing code in g0_click event,but the event is not getting fired .Is this the wrong way.Suggest me the correct way to bind data to a gridview on selecting value in dropdown and by clicking on button

<asp:DropDownList ID="ddluiversitytype" runat="server" CssClass="txtbox" AppendDataBoundItems="True" OnSelectedIndexChanged="ddluiversitytype_SelectedIndexChanged">
<asp:ListItem Value="0">--Select--</asp:ListItem>

</asp:DropDownList>
<asp:ImageButton ID="go" runat="server" ImageUrl="~/prosper_images/save.png" OnClick="go_Click" />

protected void go_Click(object sender, ImageClickEventArgs e)
{ }

vijaya