Why can't I tell when it's working?

Because Change Your Mind interacts with the unconscious mind, the conscious mind may or may not recognize the changes. I have observed many people who vehemently deny the program is working, though they are changing daily.

I have observed others who recognize subtle changes in themselves and their habits and patterns. I believe this is determined by the person's level of self awareness and ability to see themselves objectively.

Even the people who recognize their changes often go through a denial stage. The five stages of change are denial, anger, bargaining, depression, and acceptance. If you're lucky, you go through all five stages in your sleep.