Layout block is not picked up in magento, what could be. problem?

Question

Magento

There is a block that lies along the path block/adminhtml/cmslinks/grid.php
There is also a description for layout in config.xml
cmsmenu.xml
In the cmsmenu.xml file that lies in design/adminhtml/../../layout/cmsmenu .xml
At what here the first block was picked up and displayed => the file was 100% picked up!
customcmsmenu.page.tabcustomcmsmenu/adminhtml_tab_pagecustomcmsmenu.adminhtml.cmslinks.gridgetSelectedRelatedLinkslinks[related]links_relatedposition
And the actual controller file
public function gridAction()
{
$this->loadLayout();
var_dump($this->getLayout()
->getBlock('customcmsmenu.adminhtml.cmslinks.grid'));
$this->renderLayout();
}
Returns false!