overall issue with script ajax tiil now

asp:UpdatePanel ID="Panel1" runat="server">     <ContentTemplate>     <asp:GridView ID="grid1" runat="server">       <Columns>       <asp:TemplateField>         <ItemTemplate>                  </ItemTemplate>         <HeaderTemplate>         <span onmouseup="MouseUp(this);">Test</span>         </HeaderTemplate>       </asp:TemplateField>       </Columns>     </asp:GridView>     <asp:Button ID="b1" runat="server" OnClick="b1_Click" Text="" />     </ContentTemplate>     <Triggers>     <asp:AsyncPostBackTrigger ControlID="b1" />     </Triggers> </asp:UpdatePanel> protected void btnpb_Click(object sender, EventArgs e)     {     try     { // executiing a sql query for getting a condition depending on which teh control will be visible true/ fasle if (reader["status"]=="A")       div1.Visible = true; else if (reader["status"]=="B")   {     dropdown1.visible = true populatedropdown(); } else {    textbox1.Visible = true; }        }     catch     {     }     } Javascript <script type="text/javascript">       function MouseUp(e) { // this script will be executed wen the grid header cell is clicked     document.getElementById('<b1').click();     } </script> i have the above code issues faced 1)the time to populate & display the drop-down takes much longer time 2) when the grid header cell is clicked once depending on the condition a control will be visible    if i again click another header cell wthout  making the display control visible false the javascript is not getting executed 3)it works fine in FF  but in IE if i dont give alert in script the button event doesnot get fired