Added a new search option in order list page for displaying only purchase order orders

I am using nopcommerce 2.60

I need a checkbox for displaying only purchase order orders on button search click.

here are the following steps i did..

I have added new property to OrderListModel

public bool PaymentMethod {    get ;     set ; }

In order controller, in List() method, i have added the following line

model.PaymentMethod = false;

and in view i have added the following code

<tr>
            <td class="adminTitle">
                @Html.NopLabelFor(model => model.PaymentMethod):
            </td>
            <td class="adminData">
                @Html.EditorFor(model => Model.PaymentMethod)              
            </td>
        </tr>

in the view i have also added the following in  function onDataBinding(e)

PaymentMethod: $('#@Html.FieldIdFor(model => model.PaymentMethod)').val()


The problem is whenever i click on search button or whenever page is loaded for the first time, the model.PaymentMethod is always true....

I need the model.PaymentMethod to change whenever i check or uncheck

May i know what mistake i have done???