I have recently bought a rice cooker (reputable brand - sunbeam I think) but when I use it, the rice sticks to the bottom and starts to go burnt looking I've followed the instructions in the manual and apparently I don't have to set a timer or temp, just flick the button and it cooks until it sets itself to warm. What am I doing wrong???? it's been brown rice both times I've used it and that's the main reason I convinced DH to buy one as brown rice takes longer to cook.