Using event function multiple times

Hi, I am using the event function whilst solving a system of ODEs but I would like to find where multiple functions are 0. I've tried using:

function [value,isterminal,direction] = event_function(eta,X)

value = X(1) & X(2) & X(3) & X(4);     
isterminal = 1;   
direction = 0;

But this doesn't work. Does anybody know how to get round this?

[Azzi Abdelmalek]

What is the value of X?