Hello Snamyna,
You can do so by adding a
TriggerPostback
client side JavaScript function in parent page and invoke that from the onClientClick event of your LinkButton.
function TriggerPostBack(control, arg){
__doPostBack(control, arg);
}
Your
OnClientClick
function can be re-written as
<asp:LinkButton id="linkButton1" runat="server" Text='<%# Eval("DESC_T")%>' CommandName = "ViewHeader" OnClientClick="javascript:window.parent.TriggerPostBack('linkButton1', YOUR ARGUMENT);"></asp:LinkButton>
Regards,