.net - Linkbutton Doesn't Work For Updatepanel

i have set of link buttons outside update panel but when click any one of them they donot work at all , when i set the postbackUrl they make full postback my source code :

<asp:Panel ID="pnl_viewImages" runat="server">
<asp:Label ID="lbl_viewImages" runat="server" style="texalign: left"
Text="view images :"></asp:Label>
<br />
<br />
<br />
<table cellpadding="0" cellspacing="0" style="width: 100%" class ="Alternating">
<tr>
<td colspan="5">
<asp:UpdatePanel ID="updatePnl_image" runat="server">
<ContentTemplate>
<asp:ListView ID="lv_showImages" runat="server">
<ItemTemplate>
<asp:Image ID="img_showNewsImage0" runat="server" Height="300px"
ImageUrl='<%# "RetreiveImage.ashx" %>' Width="413px" />
</ItemTemplate>
</asp:ListView>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="lbtn_first" EventName="Click" />
<asp:AsyncPostBackTrigger ControlID="lbtn_last" EventName="Click" />
<asp:AsyncPostBackTrigger ControlID="lbtn_next" EventName="Click" />
<asp:AsyncPostBackTrigger ControlID="lbtn_previous" EventName="Click" />
<asp:AsyncPostBackTrigger ControlID="lbtn_delete" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
</td>
</tr>
<tr>
<td>
<asp:LinkButton ID="lbtn_first" runat="server" onclick="lbtn_first_Click">first</asp:LinkButton>
</td>
<td>
<asp:LinkButton ID="lbtn_previous" runat="server" onclick="lbtn_first_Click"><<</asp:LinkButton>
</td>
<td>
<asp:LinkButton ID="lbtn_next" runat="server" onclick="lbtn_first_Click"
>>></asp:LinkButton>
</td>
<td>
<asp:LinkButton ID="lbtn_last" runat="server" onclick="lbtn_first_Click">last</asp:LinkButton>
</td>
<td>
<asp:LinkButton ID="lbtn_delete" runat="server" onclick="lbtn_first_Click">delete</asp:LinkButton>
</td>
</tr>
</table>
<br />
</asp:Panel>`

i tried to remove the table but in vain it does not work also.