Hi,
I have solved it by taking Id on mouse over and storing to a hidden variable. Now my problem is solved. Anyway thanks for your support
<asp:ImageButton ID="imgPlus" runat="server" ImageUrl="~/images/grd_Plus.png" ToolTip="Expand" CommandName="Expand" CommandArgument='<%#Eval("CategoryName")+"^QuoterView"%>' OnClientClick='<%# String.Format("ShowSummaryView(\"{0}\");return false;", Eval("CategoryName")+"^QuoterView") %>'
onmouseover="plusid(this.id);" CssClass="imgPlus handPointer" />
function plusid(id) {
$('#hdnRowId').val(id);
var lastFive = id.substr(id.length - 5); // => "id full value"
var lastChar = id.substr(id.length - 1); // => "0"
$('#hdnRowId').val(lastChar);
return true;
}