Daily 600 net calories, no weight lost. What's wrong?

You're not eating enough and your body is angry about it.

^ this.

Read: http://www.myfitnesspal.com/topics/show/654536-in-place-of-a-road-map-2-0-revised-7-2-12

Eat.

Yep - this^

A 2 pound a week goal is for someone that's more than 75 pounds overweight. Really aggressive weekly goals make it hard for your body to support lean muscle mass. If you want a number on the scale....fast works. If you want a lower body fat %...moderate works better.