I don't know if you have called the monster void anywhere in your code.. Unless I am missing something which you changed later (going off the code in post #12 here).
Your parameters suggest that it is a collide callback, which means that you have to collide with something before it happens. You could simply move the lines within the monster void to the appropriate case, or set up a timer instead of a collidecallback.
Also, not really required, but remember that the time idle at a pathnode should be a float (may need to fix that on the tutorial on the wiki). So you MAY need to add the appropriate f, like so:
AddEnemyPatrolNode("engineer_1", "PathNodeArea_1", 0.0f, "");
AddEnemyPatrolNode("engineer_1", "PathNodeArea_2", 0.001f, "");
AddEnemyPatrolNode("engineer_1", "PathNodeArea_3", 0.0f, "");
Also note that 0 does not mean 0 time at the pathnode, however the 0.001 is the closest to practically no time. If there are more pathnode, be sure to add them to the coding in the similar ways as above, and make sure that the same number of pathnodes are in your Level