Why am I getting error while creating dropdownlist in one column of jqxgird?

Question

I have created one grid using jqWidget. I'm trying to put the drop-down list in the 7th column of jqxgrid. My code is as follows. I can't get the expected output.

// Data which I want to get in dropdownlist
var drpSource = [
        { id: 1, name: "Edit" },
        { id: 2, name: "SendMail" }
];

// This is particular 'column' part of my grid
 columns: [
                { dataField: 'user_name', text: 'Username', },
                { dataField: 'first_name', text: 'First Name', },
                { dataField: 'last_name', text: 'Last Name', },
                { dataField: 'email', text: 'Email', width: 300 },
                { dataField: 'register_dt', text: 'Registered Date', cellsformat: 'MM/dd/yyyy', },
                { dataField: 'expiration_dt', text: 'Expiry Date', cellsformat: 'MM/dd/yyyy', },
                {
                    width: 100, autoshowfiltericon: false, dataField: 'drpfunction',  text: "Function", columntype: 'dropdownlist',
                    createeditor: function (row, cellvalue, editor) {
                            editor.jqxDropDownList({
                            source: drpSource,
                            displayMember: 'name',
                            valueMember: 'id',
                            filterable: false,
                            placeHolder: 'Choose…',
                            autoDropDownHeight: true
                        });
                    },
                     initeditor: function (row, cellvalue, editor) { 
                         editor.jqxDropDownList('selectItem', cellvalue);
                     }
                 }

Am I missing anything?

Note: Column has been created successfully, Although it's blank.