How to find control inside GroupFooterTemplate of radgrid using javascript?

I need label "lblInvoiceTotal" that control? how to find the control which is in "GroupFooterTemplate" and how to assign some value(integer value) to it?? In JavaScript only, Client Side?
My code is below----------

<telerik:RadGrid ID="radgridStudentInfo" runat="server" AutoGenerateColumns="false" ShowFooter="True"
OnItemDataBound="radgridStudentInfo_ItemDataBound" OnPreRender="radgridStudentInfo_PreRender" OnItemCommand="radgridStudentInfo_ItemCommand"
GroupingSettings-RetainGroupFootersVisibility="true" Height="100%" Width="100%" OnNeedDataSource="radgridStudentInfo_NeedDataSource">
<ClientSettings>
<Scrolling AllowScroll="false" />
</ClientSettings>
<MasterTableView ShowGroupFooter="true" AllowMultiColumnSorting="true" GroupLoadMode="Client" DataKeyNames="OrganizationID,JobID,CandidateID,AgencyID,MainInvoiceID,OrderType,RefInvoiceId,WeekNo,OrientationAmt,CommissionAmount,TotalPenaltyAmt,InvAdjustedAmount,OTHours,OTRate,OncallHours,OncallRate,ChargeHours,ChargeRate,CallbackHours,CallbackRate,ExtendedDayRate,ExtendedDayHours,ExtendedNightRate,ExtendedNightHours,ExtendedWeekEndRate,ExtendedWeekEndHours,HolidayRate" ShowHeadersWhenNoRecords="true">
<GroupFooterTemplate>
<itemstyle horizontalalign="Right" />


<table style="width: 100%">
<tr>
<td colspan="1" style="text-align: left">
<asp:Label ID="lblInvoiceTotal" runat="server" Style="font-weight: bold;" ></asp:Label>
</td>
<td colspan="9" style="font-weight: bold; text-align: right">
<asp:Label ID="lblInvoicePaidText" Text="Amount to be Paid:" Style="font-weight: bold;" runat="server"></asp:Label>
</td>
<td colspan="1" style="text-align: right">
<asp:Label ID="lblInvoicePaid" runat="server" Style="font-weight: bold;" Text="Invoice Paid"></asp:Label>
</td>

</tr>
</table>
</GroupFooterTemplate>
<Columns>
<telerik:GridTemplateColumn HeaderStyle-Width="30px" UniqueName="CheckBoxall">
<HeaderTemplate>
<asp:CheckBox ID="radChkSelectAll" runat="server" AutoPostBack="true" OnCheckedChanged="radChkSelectAll_CheckedChanged" />
</HeaderTemplate>
<ItemTemplate>
<asp:CheckBox ID="radChkSelect" AutoPostBack="true" runat="server" OnCheckedChanged="radChkSelect_CheckedChanged" onclick="checkBoxClick(this, event);"/>
</ItemTemplate>
</telerik:GridTemplateColumn>


<telerik:GridBoundColumn DataField="OrgName" HeaderText="Organization">
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="LocationName" HeaderText="Location">
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="DeptName" HeaderText="Department">
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="JobTitle" HeaderText="Job Title">
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="Skill" HeaderText="Skill">
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="CandidateName" HeaderText="Candidate Name">
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="PlaceFeePercentage" HeaderText="Placement Fee %" UniqueName="PlaceFee" Display="false">
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="AnnuSalary" HeaderText="Annual Salary" UniqueName="AnnSalary" DataFormatString="{0:$###,##0.00}" Display="false">
<ItemStyle HorizontalAlign="Right" />
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="BillRate" HeaderText="Bill Rate" DataFormatString="{0:$###,##0.00}" UniqueName="BillRate" HeaderStyle-HorizontalAlign="Right">
<ItemStyle HorizontalAlign="Right" />
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="Bonus" HeaderText="Bonus" DataFormatString="{0:$###,##0.00}" UniqueName="Bonus">
<ItemStyle HorizontalAlign="Right" />
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="TotalHours" HeaderText="Total Hours" UniqueName="TotalHours" Display="false">
</telerik:GridBoundColumn>
<telerik:GridBoundColumn HeaderText="Week No" DataField="WeekNo" HeaderStyle-HorizontalAlign="Right">
<ItemStyle HorizontalAlign="Right" />
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="WeekDates" HeaderText="Week Period">
</telerik:GridBoundColumn>
<telerik:GridButtonColumn CommandName="View" HeaderText="Week Hours" DataTextField="WeekHours" ButtonType="LinkButton" UniqueName="View" HeaderStyle-HorizontalAlign="Right">
<ItemStyle HorizontalAlign="Right" />
</telerik:GridButtonColumn>


<telerik:GridBoundColumn DataField="SubTotalAmount" HeaderText="Sub-Total Amount" DataFormatString="{0:$###,##0.00}" Display="true" UniqueName="SubTotalAmount">
<ItemStyle HorizontalAlign="Right" />
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="SubTotalAmount" HeaderText="Invoice Amount" DataFormatString="{0:$###,##0.00}" UniqueName="TotalAmount" HeaderStyle-HorizontalAlign="Right">
<ItemStyle HorizontalAlign="Right" />
</telerik:GridBoundColumn>
<telerik:GridBoundColumn DataField="InvoiceDetailsID" HeaderText="InvoiceDetailsID" UniqueName="InvoiceDetailsID" Display="false">
</telerik:GridBoundColumn>
</Columns>
</MasterTableView>
<ClientSettings AllowDragToGroup="false" />
<GroupingSettings ShowUnGroupButton="false" />
</telerik:RadGrid>


And the javaScript function i am using is below----------

function checkBoxClick(sender, args) {
debugger;
var masterTable = $find("<%=radgridStudentInfo.ClientID%>").get_masterTableView();
var Amt=0;
var count = masterTable.get_dataItems().length;
var checkbox;
var totalAmt = 0;
var SubTotal;
var strAmount = 0;
var item;

for (var i = 0; i < count; i++) {
item = masterTable.get_dataItems()[i];
checkbox = item.findElement("radChkSelect");

SubTotal = masterTable.getElementById(masterTable.getElementById("lblInvoiceTotal").value);


if (checkbox.checked) {
Amt = masterTable.getCellByColumnUniqueName(masterTable.get_dataItems()[i], "SubTotalAmount").innerHTML;
Amt = Amt.replace(",", "")
strAmount = parseFloat(Amt.replace("$", ""))
totalAmt = totalAmt + strAmount;
}

}
InvoiceTotal = totalAmt;

}