php - validation engine ajax error 200 parsererror in Codeigniter -

i want existing email check validation engine.but there problem showing in firebug console below:

php error encountered

severity: notice

message: undefined index: reg_em

filename: controllers/user.php

line number: 170

["email",true]

ajax error: 200 parsererror

here jquery.validationengine-en.js:

"ajaxcheckemail": {                 "url": base_url+"user/checkemailexistence/",                 "extradatadynamic": ['#reg_em'],                 "alerttextok": "* email available",                 "alerttext": "* email taken",                 "alerttextload": "* validating, please wait"             }, 

view of email field:

<input type="text" class="text_item_val_style validate[required,ajax[ajaxcheckemail],custom[email]]" name="useremail" id="reg_em" style="height:21px;"/> 

controller:

function checkemailexistence(){

   $email        = $_request['reg_em'];    $getstatus = $this->users->existing_email_check($email);    echo $getstatus; 

}

model:

function existing_email_check($email){     $valid  = true;     $rs     = $this->db->where('email', $email)->get('users');     if($rs->num_rows() > 0){         $valid  = false;     }     $rs->free_result();     $arr    = array('email',$valid);     return json_encode($arr); } 

instead of $email = $_request['reg_em']; write $email = $_request['useremail'];