flex mxml && 问题

<mx:Button label="确定" textAlign="right"  visible="{this.currentState=='simple' && !(_retailBill || _businessBill)}" includeInLayout="{this.currentState=='simple' && !(_retailBill || _businessBill)}" id="commit" click="onCommitFunction(event);"/>

上面那种写法会报错 编译不能通过

<mx:Button label="确定" textAlign="right"  visible="{this.currentState=='simple' &amp;&amp; !(_retailBill || _businessBill)}" includeInLayout="{this.currentState=='simple' &amp;&amp; !(_retailBill || _businessBill)}" id="commit" click="onCommitFunction(event);"/>

改成这样就Ok