I am getting this javascript error "unexpected call to method or property access"

[aloksingh83]

This error coming when i am using telerik grid.It works fine in asp.net grid
what i am trying to do is taking values from textbox and show in grid view...
here is the code:

 <script language="javascript" type="text/javascript">

        function AddItems() {
            var lgrd = document.getElementById('<%=RadGrid1.ClientID%>');
            var ltxtSystemId = document.getElementById('<%=txtSystemId.ClientID%>');
            var ltxtReportTitle = document.getElementById('<%=txtReportTitle.ClientID%>');
            var ltxtsysid = document.createTextNode(ltxtSystemId.value);  //nodevalue =ltxtSystemId.value
            var ltxtRptTtle = document.createTextNode(ltxtReportTitle.value);
            var tr = document.createElement("tr");
            var cell1 = document.createElement("td");
            var celln = document.createElement("td");

            cell1.innerHTML = ltxtsysid.nodeValue;
            celln.innerHTML = ltxtRptTtle.nodeValue;
            tr.appendChild(cell1);
           
            tr.appendChild(celln);
            lgrd.firstChild.appendChild(tr);
        }

</script>

 <asp:TextBox ID="txtSystemId" runat="server" ></asp:TextBox>
        <asp:TextBox ID="txtReportTitle" runat="server" ></asp:TextBox>
        <input type="button" id="btnMinfileNo" style="width:14%;height: 42px;" value="Add" 
        onclick="return AddItems()" />&nbsp;&nbsp;

        <asp:GridView ID="GridView1" runat="server"  
        Height="100px" Width="100px" >
        </asp:GridView>
        <telerik:RadGrid ID="RadGrid1" runat="server" >
        </telerik:RadGrid>

[Plater]

Sounds like a question for telerik, since it's not a native .NET object.
My guess is you're calling a function not available on that grid object.