How to make checked a checkbox which is in closed modal?

I have this modal :

<div class="modal fade" id="column-settings-modal" tabindex="-1" role="basic" aria-hidden="false">

And this checkbox in the modal :

<input type="checkbox" id="partcountry-cb" value="Ülke"  />  &nbsp; Ülke <br />

I have a function to load modal. And I want to chekc this checkbox while modal is opening.My function is below :

function load_column_filters(surveyId,toShow) {

var $modal = $('#column-settings-modal');


 $modal.modal();
 $("#partcountry-cb").attr("checked", true); 
}

However the last statement does not work. (I have tried .prop it does not work too.) Is this problem about modal itself or am I missing something? Thanks for any help.