If this is a young burm, there is probably something wrong with your set up (cage size, lack of proper hide areas, improper temps, improper humidity levels, improper substrate, etc....could be one factor, could be multiple factors). Since you didn't provide any information on how this animal is being kept, it would be remiss of us to even make a guess. But, with that being said, and, assuming (which I don't but for the sake of answering this question, I will), that you are providing the proper care of this snake, you might try the following (and don't use the "I can't afford it" excuse; you took the responsibility of owning the snake and now its your responsibility to do everything in your power to ensure that it is properly cared for):
1) Offer food IN the cage (hopefully you are already doing that)
2) Offer food when the lights are subdued in the room the snake is in.
3) Offer food only when the burm is inside its hide area
4) What did the snake eat the last time?...if it was a mouse, then offer a f/t mouse. If the snake accepts it, you can always trail a rat which is a very simple and effective technique
5) Try offering a quail (you can get them at rodentpro.com); burms LOVE birds and this is a great food source for stubborn feeders
6) Try offering live prey; this should be a last ditch effort but worth trying if all else fails
Once again, check all of the variables of your husbandry. Also, I would highly recommend doing a fecal check with your vet to rule out parasites or any disease it may have. Bottom line is, if this is a young burm, or hatchling, it should be feeding regularly.
Rob Carmichael, Curator
The Wildlife Discovery Center at Elawa Farm
City of Lake Forest, IL