Scratch

Usually, it means that you should have a Wait inserted somewhere.  What happens a lot of times is the Green Flag is clicked and a lot of variables go to zero and a lot of processes get fired off.  Sometimes the processes fire first, before the variables have had a chance to zero out completely.  If you pay close attention to what processes depend of initial variable conditions and make sure they wait a fraction of a second before starting (to give the variables time to get set), you can usually cure the double click problem.

what happens to me is that the variable is zero when you end the game, which is what the game is like when the green flag is clicked. But then my "If variable=0 broadcast end" broadcasts before the variable is not zero.

But you put them in seperate scripts. For your broadcast gameover thing just go
=====
when greenf;ag clicked
wait (1) secs
forever
if <var = 0>
======