Combobox as editor inside grid - Clicking down arrow throws error

hi,
I am using RowEditor functionality..

Below is my Grid Panel code

<ext:GridPanel ID="Grid_Education" runat="server" Border="true" Height="580" Title="">
<Store>
<ext:Store ID="Store_Education" runat="server" AutoLoad="true">
<Reader>
<ext:JsonReader>
<Fields>
<ext:RecordField Name="Degree" />
<ext:RecordField Name="Institute" />
<ext:RecordField Name="Grade_Percentage" />
</Fields>
</ext:JsonReader>
</Reader>
</ext:Store>
</Store>
<Plugins>
<ext:RowEditor ID="RowEditor1" runat="server" SaveText="Update" />
</Plugins>
<View>
<ext:GridView ID="GridView1" runat="server" MarkDirty="false" />
</View>
<TopBar>
<ext:Toolbar ID="Toolbar1" runat="server">
<Items>
<ext:Button ID="Button1" runat="server" Text="ADD EDUCATION" Icon="UserAdd">
<Listeners>
<Click Fn="addDegree" />
</Listeners>
</ext:Button>
<ext:Button ID="Button2" runat="server" Text="REMOVE EDUCATION" Icon="UserDelete">
<Listeners>
<Click Fn="removeDegree" />
</Listeners>
</ext:Button>
</Items>
</ext:Toolbar>
</TopBar>
<SelectionModel>
<ext:RowSelectionModel ID="RowSelectionModel1" runat="server" />
</SelectionModel>
<ColumnModel>
<Columns>
<ext:RowNumbererColumn />
<ext:Column Header="Degree" DataIndex="Degree" Width="220" Sortable="true">
<Editor>
<ext:ComboBox ID="Degree" runat="server" AllowBlank="false" DisplayField="DegreeName"
ValueField="DegreeId" TypeAhead="true" Mode="Local" ForceSelection="true" TriggerAction="All">
<Store>
<ext:Store runat="server" AutoLoad="true">
<Reader>
<ext:JsonReader>
<Fields>
<ext:RecordField Name="DegreeId" />
<ext:RecordField Name="DegreeName" />
</Fields>
</ext:JsonReader>
</Reader>
</ext:Store>
</Store>
<Listeners>
<Focus Scope="this" Handler="el.onTriggerClick();" Buffer="50" />
</Listeners>
</ext:ComboBox>
</Editor>
</ext:Column>
<ext:Column DataIndex="Institute" Header="Institute / Certification Body">
<Editor>
<ext:TextField ID="Institute" runat="server" AllowBlank="false" />
</Editor>
</ext:Column>
<ext:Column DataIndex="Grade_Percentage" Header="Grade / Percentage">
<Editor>
<ext:TextField ID="Grade_Percentage" runat="server" AllowBlank="false" />
</Editor>
</ext:Column>
</Columns>
</ColumnModel>
</ext:GridPanel>



Here is the script:

<ext:XScript ID="XScript1" runat="server">
<script type="text/javascript">
var addDegree = function () {
var grid = #{Grid_Education};
grid.getRowEditor().stopEditing();

grid.insertRecord(0, {
Degree : "",
Institute : "",
Grade_Percentage : ""
});

grid.getView().refresh();

grid.getSelectionModel().selectRow(0);
grid.getRowEditor().startEditing(0);
}
</script>
</ext:XScript>


It throws some error in metadata of aspx file in the line : B=new Function(p,y,c+e+p+"; }")
Microsoft JScript runtime error: Object doesn't support this action..
Could some one help me on this....