getting An AJAX HTTP error occurred. HTTP Result Code: 200

I GET THE MODAL FORM POPUP,ITS showing well.
when i submit, a value on validation everything works well,i mean the error messages are displayed on the form.
but when is reaches the submit i am getting this error "An AJAX HTTP error occurred. HTTP Result Code: 200".
with if logged in as adminstrator it shows lots of debugging informations which i dont understand. I have attached a Screen shot for both on validation and on submit.
THE STRANGE THING IS THAT THE VALUES ARE SAVED TO THE DATABASE...SO I GUESS THERE MUST ISSUE WITH REDIRECT!!
HELP PLA

//here is my validate function

/***
 *implementation of hook_validate()
 *@ $form_state takes the current state of a form and the submited values
 *@ &$form we are also passing the whole drupal form as a refference
 *Validate the kupon number submitted by user
 */
function freechuz_get_kupon_form_validate(&$form,$form_state){
        
         $productid=$form_state['values']['product_id'];
         $submitted_coupon=$form_state['values']['coupon_qty'];
	 $coupon_left=coupon_left($productid);
	 if (!is_numeric($submitted_coupon)) {
	    form_set_error('coupon_qty',t('You must enter a number for the kupon'));
	}elseif (($submitted_coupon)<1){
	    form_set_error('coupon_qty',t('The value of Kupon must be greater than Zero.'));
	}elseif($productid<0){
	  form_set_error('coupon_qty',t('Sorry product number undifined, try again later'));
	}elseif($coupon_left==0){
	  form_set_error('coupon_qty',t('Вы уже получили этот купон!'));
	}
}

//implemenation of hook_submit()

/**
 *submit the kupon to database via hook_submit 
 */
function freechuz_get_kupon_form_submit(&$form,$form_state){
    global $user;
    global $base_path;
  
    //call the submit coupon function
   if(submit_kupon($form_state['values']['product_id'],$form_state['values']['coupon_qty'])){
    drupal_set_message(t('<font color="green" size="4">Купон получен!!! Ваш купон доступен в <a href="'.$base_path.'user/'.$user->uid.'/freechuzkupon">личном кабинете.</a></font><br/>'));
  
   }else{
   
    drupal_set_message(t('<font color="red" size="4">Sorry something went wrong, try again later</font><br/>'));
    
   }

}

/*********submit function**********/
/**
 *submit the kupon to database
 *@param $productid the id of the product or simply nodeid
 *@param $coupon_qty how many coupons per product
 */
function submit_kupon($productid,$submitted_coupon){
    global $user;
    $counter=0;
    $coupon_left=coupon_left($productid); //left coupon
    $result='';
  if(($submitted_coupon<=$coupon_left)){  
  /**
    * update the coupon sold value for user with the submitted values
    */
     $node=node_load($productid); //load the node
     $node->field_coupon_sold['und'][0]['value']=$node->field_coupon_sold['und'][0]['value']+$submitted_coupon;
     print 'coupon sold '.$node->field_discount_value['und'][0]['value'];
     node_save($node); //then update, save the node
     /***end of update coupon sold***/
    
  while($counter<=($submitted_coupon-1)){
    $coupon_number=coupon_generate(16);//generate the coupon
    $result=db_insert('freechuz_coupon')
     ->fields(array(
    'coupon_number' =>$coupon_number,
    'content_id' => $productid,
    'coupon_qty' => $submitted_coupon,
    'deleted' => 0,
    'user_id' =>$user->uid
    ))
    ->execute();
    //in the future will add a unique number(generated from coupon id) to each coupon generated
    $counter++;
   }
  } 
   if($result){
      return true;
    }else{
        return false;
    }
}

?>