Why can't I run krumo() on a node page? I called krumo() inside hook_node_load().

function mymodule1_node_load($nodes, $types) {
    krumo($nodes);
}


It works on my front page, but not on a node page. I get this error message:


  Fatal error: Call to undefined function krumo() in C:\wamp\vhosts\mydrupal72\sites\all\modules\my_customs\mymodule1\mymodule1.module on line 126


Why can't I run krumo() on a node page?
An option would be using module_load_include(). Manually making sure it's loaded