I am not able to click on filter on grid in selenium : I am giving the code below where i need to click on the filter icon. please help me out 
    <thead class="k-grid-header" role="rowgroup">
    <tr role="row">
    <th class="k-header k-filterable k-with-icon" scope="col" data-title="User Name" data-index="0" data-field="UserName" data-role="columnsorter">
    <a class="k-grid-filter" href="javascript:void(0)" tabindex="-1">
    <span class="k-icon k-filter"/>
    </a>
    <a class="k-link" href="/Admin/AdminRoleGrid/Read?adminGrid-sort=UserName-asc">User Name</a>
    </th>