I want to append a BS alert to a JS condition. It appears to work in that the alert message is displayed, EXCEPT when appended, the BS fade JS does not work so the message stays permanently on the page. I'm new to JS, and don't know who to get this to work.

How do I append the alert message so that the alert JS continues to function ?

HTML Code:
 <div id="alertMessage">   </div>

$(document).ready(function () {

    $("input.btn").mousedown(function () {      // THIS IS THE SUBMIT BUTTON OMN THE FORM
        var required = $("input.required").val();  // WE GRAB THE VALUES OF THE "REQUIRED FIELDS"

        if (required == "") {                   // IF ANY OF THE REQUIRED FIELDS ARE EMPTY WE EXECUTE THE FOLLOWING:

            var message = '<p class="alert alert-danger fade in" > You have Missed Off One or More Required Fields !</p>'