What you have to do is to isolate the problem, even if it means putting echo statements incrementally through your code to see what gets executed. Start an echo statement where you think the code should start putting out the months, and see if it is looping properly, etc. You will innevitably find the source of the problem as some of the echo statements you think should be put to the screen will not do so. Either that or start with a smaller bit of code to debug, and then slowly add the extra.

ie. use the scientific method... experiment and test. Trying to get one big piece of code working without testing the parts is insane :) not to mention impossible.