Who's really "Baby Wise"? - Me or her??

I am not sure I get this whole Baby Wise thing. I have been trying to get her on a schedule. The "book" says she should eat every 2.5-3 hours and during the day she does. At night she usually goes 5 hours without eating. Not too bad. Well lately she in inconsolable in the evenings. She seems to want to eat after just 2 hours or even less sometimes. I tried to just let her cry in her bed tonight - for about 45 min all together - and all I had at the end was a very angry baby. I went ahead and fed her because I really didn't know what else to do. According to the book it seems like she should be on a schedule, but I can't seem to get it to work. What the heck am I doing wrong? They need like a Baby Wise help line or something. Well, the crying has finally stopped and I am just hoping she is asleep in there...