confirmation for link_to not working rails 4

I have the following code-

<td><%= link_to "", {:controller => :daily_work_updates, :action => :deleteValue, :id => a.UPDATE_ID}, data: {confirm: "Are you sure?"} , :class=>'glyphicon glyphicon-trash'%></td>

When I click on the link. The action is successfully done but the confirmation pop up does not show for some reason. I have looked up similar questions but none have seemed to help me.

I am using rails 4.