Exibir em echo onmouseover onmouseout

Beleza galera empaquei novamente :) nao estou conseguindo usar a funçao onmouseover onmouseout dentro do php

<?php
$product = Mage::getModel('catalog/product')->load($_product->getId());
$helper = Mage::Helper('catalog/image');
$limit = 1;
$count = 0;

foreach ($product->getMediaGalleryImages() as $image) {

 if($count < $limit){
 echo "
 <img src='" . $this->helper('catalog/image')->init($this->getProduct(), 'thumbnail', $image->getFile())->resize(135) . "'
 onmouseover='" . $this->helper('catalog/image')->init($this->getProduct(), 'thumbnail', $image->getFile())->resize(135) . ";'
 onmouseout=" . $this->helper('catalog/image')->init($_product, 'small_image')->resize(135) . ";'/>";

 }
 $count++;
}
?>