What should a devotee do when material desires start increasing and chanting doesn’t help?

Question: It is said that the practice of Krishna consciousness will decrease one’s material desires. Yet many practicing devotees find that material desires start increasing for no apparent reason. Why does this happen? It is said that chanting will drive away those desires. What does one do when that doesn’t happen? How can we understand when chanting, which is the yuga-dharma for this yuga, doesn’t work?