My bamboo tablet only works when itouch it with my fingers, but not with the pen?

[Anime4Life1]

well up till yesterday my pen was working fine but all of a sudden today i wanted to use it but it only works when my fingers touch it..like the light is blue when i touch it but when the pen touches it the light turns orange..what should i do..and i already tried clicking the buttons on the tablet but it didnt work