Odd FF/IE behavior with the .hide() method

Odd FF/IE behavior with the .hide() method

Odd behavior In FF i get an error that simply says undefined, in IE it works:
 
    $("#msgresults").html(json);
    $("#myform").hide();
 
In FF this works:
 
 
    $("#myform").hide();
    $("#msgresults").html(json);
all that is switched is the order of the calls.  The divs are as follows:
 
<div data-role="content">
    <div id="myform"> 
        <form method="post" action="mobileverify.php" id="loginform">
            <fieldset data-role="fieldcontain">
            <legend>Login Information</legend>
                <label for="uname" class="ui-hidden-accessible">Username: </label>
                <input type="text" name="uname" id="uname" value=""
                placeholder="Username" >
                <label for="mpass" class="ui-hidden-accessible">Password: </label>
                <input type="password" name="mpass" id="mpass" value="" placeholder="Password">
            </fieldset>
                 <input name="login" type="submit" value="Login"  id="login" data-icon="arrow-r" data-iconpos="right">
                 <input name="cmd" type="hidden" value="login">    </form>
    </div><!--END FORM-->












    <div id="msgresults"></div> 
</div><!--END CONTENT -->
 
Any thoughts??