Why is my fondue cheese sauce chunky?

Ok so I got a new fondue pot and had to try it out. I tried to do the Fiesta cheese fondue from The Melting Pot but the cheese was not the texture I wanted. They told me to mix flour with the cheese because it helps it melt, but it was just a little off. I don't think I waited long enough for the pot to get hot enough, do you think that was the problem?Why is my fondue cheese sauce chunky?
Try to add the cheese a little at a time, constantly stirring with a fork or a whisk. The high heat may have caused some problems, depending on what kind of cheese it was. Try heating the fondue over medium-low heat next time.
We just melt the cheese with a little cream...you may add other flavors to your cheese sauce also..like dillweed,creamcheese,garlic,tabasco etc.....

I have never added flour and do not see the point.Why is my fondue cheese sauce chunky?
you have to cook flour before you add. just strain the cheese, and reheat.