Filter Datetime field with datetimepicker

[umar]

i have used date time field with datepicker now i gets problem in find control .in below code..check code properly and reply as soon as possible.
 <telerik:GridDateTimeColumn  FilterControlWidth="120px" DataField="order_date" HeaderText="ORDER DATE" 
                        UniqueName="order_date" PickerType="DatePicker" DataFormatString="{0:D}" SortExpression="order_date" AllowFiltering ="true">
                        <HeaderStyle Width="160px" />



 if (filterPair.First.ToString() == "EqualTo")
            {
                                   string colName = filterPair.Second.ToString();
             //Here i gets problem--->       TextBox tbPattern = (e.Item as GridFilteringItem)[colName].Controls[0] as TextBox;
                    string values = tbPattern.Text;
                    string newFilter = "(([" + filterPair.Second + "] =" + values + "))";
                    DataTable dt = new DataTable();
                    dt = Session["dt"] as DataTable;
                    DataTable dtNew = new DataTable();
                    dtNew.Columns.Add("order_id");
                    dtNew.Columns.Add("order_date");
                    dtNew.Columns.Add("items_selected");
                    dtNew.Columns.Add("total_amount");
                    dtNew.Columns.Add("order_description");
                    dtNew.Columns.Add("username");
                    dtNew.Columns.Add("status");
                    DataRow row;
                    e.Canceled = true;