Pagination problem: Same pages showing differents products and order

Hi everyone,

This is my first post in the forum, I have a problem with our Magento site related with pagination:
1. We have created a custom date attribute for our catalog products
2. The pagination is configured to sort the elements by default using the custom date attribute in descending mode.
3. Accessing to the section/page with pagination, when you change the pages you can see that for the same page Magento does not show the same elements in the same order.
For example, you navigate to page 4 and see the results, change to page 3 and then change back to page 4 and the elements and order are not he same than the first time.

I have tried the following solutions with no success:
1. Checked in System-->Catalog-->FrontEnd the two checks for use plain catalog category and use plain catalog article (with no effect after reindexing).

2. Tried to create an event catalog_product_collection_load_before in order to add a second sort condition when the collection is obtained, but not sure if its working or not (the pagination still working in the same way):

- /var/www/magento/app/etc/modules/Encamina_Ordenacion.xml:
<?xml version="1.0"?>
<config>
<modules>
<Encamina_Ordenacion>
<codePool>local</codePool>
<active>true</active>
<depends>
<Mage_Catalog />
</depends>
</Encamina_Ordenacion>
</modules>
</config>

- /var/www/magento/app/code/local/Encamina/Ordenacion/etc/config.xml:
<?xml version="1.0"?>
<config>
<modules>
<Encamina_Ordenacion>
<version>1.0.0</version>
</Encamina_Ordenacion>
</modules>
<global>
<models>
<encamina_ordenacion>
<class>Encamina_Ordenacion_Model</class>
</encamina_ordenacion>
</models>
</global>
<adminhtml>
<events>
<catalog_product_collection_load_before><!-- observe the event -->
<observers>
<encamina_ordenacion>
<class>encamina_ordenacion/observer</class>
<method>agregarParametroOrdenacion</method>
</encamina_ordenacion>
</observers>
</catalog_product_collection_load_before>
</events>
</adminhtml>
</config>

- /var/www/magento/app/code/local/Encamina/Ordenacion/Model/Observer.php:
<?php
class Encamina_Ordenacion_Model_Observer {
public function agregarParametroOrdenacion($observer) {
$observer->getCollection()->addAttributeToSort('sku', 'desc');
}
}
?>

Not sure if everything for the event is correct, any help withs this or any additional option to solve the problem will be appreciated.

Thanks in advance.

Best regards.

Adding a second sort parameter in the Toolbar.php file seems to solve the problem.

public function setCollection($collection)
{
$this->_collection = $collection;
$this->_collection->setCurPage($this->getCurrentPage());
// we need to set pagination only if passed value integer and more that 0
$limit = (int)$this->getLimit();
if ($limit) {
$this->_collection->setPageSize($limit);
}
if ($this->getCurrentOrder()) {
$this->_collection->setOrder($this->getCurrentOrder(), $this->getCurrentDirection());
$this->_collection->setOrder('sku', 'desc');
}
return $this;
}

Randomizing the request of the returned posts in a WordPress inquiry is simple returned arbitrarily by and by and you get an altogether unique arrangement of posts. In the wake of having this issue various occasions myself I chose to discover a route around it. so it utilizes a similar irregular request on each ensuing page load.