I have tried feeding my plant but the traps do not close very quickly, or not at all.

Slow closing traps usually means that the plant is too cold. Since this is a growth process, the warmer the plant, the quicker it will close. Try raising the temperature to around 80 degrees and see how the plant reacts. If it is still not closing properly the traps may not be fully reset from a previous closing or the light may not be bright enough.