how to global variable in function

[kofa]

hello all

onSelfEvent (load) {      
    loadV = new LoadVars();                        
    MyArray = new Array();
    loadV.load("mytext.txt");  
    loadV.onData = function(s) {
        p = s.split('&');              
        for(i=1; i < p.length; i++) {            
            MyArray[i]=p[i].split('|'); 
        }
        n = parseFloat(MyArray[1][0]);
        _global.n =n
}
    trace(_global.n)  // undefined
// here how can i use (n) variable
} 

how can i use variable n outside the function