View value in modal window with asp.net vb.net and boostrap

I want to open a modal window with boostrap in asp.net but that I change the value of a label that is in the body of the modal for that I do this

ASP.net

<!-- Button trigger modal -->
<button type="button" class="btn btn-primary btn-lg" data-toggle="modal" data-target="#myModal">
  Launch demo modal
</button>

<!-- Modal -->
<div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
        <h4 class="modal-title" id="myModalLabel">Modal title</h4>
      </div>
      <div class="modal-body">
        <Asp:label/ id text>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>

VB.net codebehind

Idlbl.text = "error en usuario inténtelo de nuevo"

I can not think of any other way to change the label according to the user's event.