Cannot read property 'mobile' of undefined at file:///android_asset/www/jquerymobile120.js:256

Cannot read property 'mobile' of undefined at file:///android_asset/www/jquerymobile120.js:256

I have included the latest jqueymobile.js  
When I click on submit button, I got the error as below:

Cannot read property 'mobile' of undefined at file:///android_asset/www/jquerymobile120.js:256


Below is code of my HTML File (index.html):

<!DOCTYPE html>
<html>
  <head>
     <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
    <link href="registrationstyle.css" type="text/css" rel="stylesheet">
    <script src="jquery.min.js"></script>
    <script src="jquerymobile120.js"></script>
    <meta charset="UTF-8" />
    <title></title>
    <style type="text/css" media="screen">
    #wrap
    {
      width:100%;           
      height:100%;
      background: #E6E6E6;
    }   
    #heading_font
    {
      width:96%;
      margin-left:2px;
      margin-right:2px;
      padding:4px 0px 4px 15px;
      background-color:#333333;
      color:#FFFFFF;
      overflow:hidden;
      border-radius:5px;"   
    }
  </style>
  </head>
  <body bgcolor="#E6E6E6">
    <div id="wrap">
      <div>
       <span style="float:left" ></span>
        <span style="float:right" ></span>
      </div>
      <br>
           <div id="heading_font">Registration</div>
           <br>
     
    
      <form class="form-container">
        <div class="form-title">
        </div>
        <div class="form-title">Cell Number</div>
        <input maxlength="10" name="mobilenumber" id="mobilenumber" class="form-field" type="number"><br>
        <br>
        <div class="form-title">Email-ID</div>
        <input maxlength="50" name="email" id="email" class="form-field" type="text"><br>
        <br>
        <div  class="submit-container">
         <input    id="submitp" onclick="validateForm()" type="submit">
        </div>
      </form>
      </div>
       <script>   
        function CallNextPage()
           {  
          document.location="SignIn.html";
        }
       
         function validateForm()  
         { 
             var mobile_number=document.getElementById('mobilenumber').value;
        
             if (/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(document.getElementById('email').value)) 
             { 
                 alert("done one");
                document.location="SignIn.html";
                alert("done two");
               
              }
              else
              {
               alert("You have entered an invalid email address!");
            }
           
            if(mobile_number.length<10)
            {
              alert("Mobile Number length cannot be less than 10");
            }          
         } 
           
   </script>
  </body>
</html>