[twitter-bootstrap] Bootstrap modal not displaying

Change you Code To something like this,

_x000D_
_x000D_
<!-- Modal -->
<div id="myModal" class="modal fade" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
  <div class="modal-header">
    <button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
    <h3 id="myModalLabel">Modal header</h3>
  </div>
  <div class="modal-body">
    <p>One fine body…</p>
  </div>
  <div class="modal-footer">
    <button class="btn" data-dismiss="modal" aria-hidden="true">Close</button>
    <button class="btn btn-primary">Save changes</button>
  </div>
</div>

<a class="btn" data-target="#myModel" role="button" data-toggle="modal">Launch demo modal</a>
_x000D_
_x000D_
_x000D_

and try using data-target="#ModelId" once. maybe it's the possible causing the issue.

Second, if you have included JQuery more then one time, remove it and include it once only. It also prevents the model sometimes.