问动态创建的<a>标记的函数不起作用

EN

anchor.onclick = rateIt(this);
anchor.onmouseover=rating(this);
anchor.onmouseout=off(this);

var that = this;
anchor.onclick = function(){ rateIt(that); };
anchor.onmouseover = function(){ rating(that); };
anchor.onmouseout= function(){ off(that); };

var addExhibits=document.getElementById('mycontent'),
rateIt=function(e){
 e=e||window.event;
 var target=e.target||e.srcElement;//polyfill for older browser
 console.log(this,target);
},
rating=function(e){
 console.log(this,e.target);
},
off=function(e){
 console.log(this,e.target);
},
mytest=function(){
 var div=document.createElement('div'),
 a=document.createElement('a');
 div.id='rateMe';
 a.id="_1"; // id's shouldn't contain _ - & numbers(1st letter) even if it works.
 a.onclick=rateIt;
 a.onmouseover=rating;
 a.onmouseout=off;
 div.appendChild(a);
 addExhibits.appendChild(div);
};