HELP! is this a Bug in the game engine?

The script says I need to assign the
variable when i already assigned it in
the script AND the inspector!!!
(I think it may be a bug)

/*UnassignedReferenceException: The variable col of ‘beyblade spin’ has not been assigned.
You probably need to assign the col variable of the beyblade spin script in the inspector.
beyblade spin.Update () (at Assets/game2/beyblade spin.js:30)
*///this is the error

var col:Collider;

function Update(){
if(col.gameObject.tag=="tag super duper")
{
print("hi");
}
}

First, your question title should summarize the problem, so other users can see at a glance what you’re having trouble with.

Are you sure that ALL gameobjects that use this script have something assigned to col? You may be looking at one correctly set up instance of the script, but the error is caused by a different one.