Low voltage indicator

Im sorry for lack of information xD

No i have a circuit. It is the very same as sparkfuns "uh oh kit"
But no matter what i do the only thing that happens is that the led is on all the time. But slightly dimmed when configurated to aprox 2.5v at tp1 of said circuit. What it SHOULD do is to light the led when voltage hit and drops below 2.5v

It could be my 10k pot thats faulty. But the only replacements i have at hand at the moment are a 75k pot and a 1M pot.

Dont want anyone to design it for me. Just some help with what i may be doing wrongly... Also i find said circuit kinda consfusing and thats rare :-/