Is this a bug of layout:accordion

Is this a bug of layout:accordion?
官方站没人在。。。还是转到国内来。。。
My code like this

{
    region:'west',
    split:true,
    width: 200,
    minSize: 175,
    maxSize: 400,
    autoScroll: true,
    layout:'accordion',
    title:'Menu Title',
    collapsible :true,
    layoutConfig:{
     animate:true
     },
    items: [
     {
      title:'Menu One',
      border:false,
      html:'<div id="tree-div" style="overflow:auto;width:100%;height:100%">Items<br />Items<br /></div>'
      //iconCls:'nav'
     },{
      title:'Menu Two',
      border:false,
      //iconCls:'settings',
      html:'<div id="tree" style="overflow:auto;width:100%;height:100%">Items<br />Items<br />Items<br /></div>'
     },{
      title:'Menu Three',
      border:false,
      //iconCls:'settings',
      html:'<div id="tree3" style="overflow:auto;width:100%;height:100%">Items<br />Items<br />Items<br /></div>'
     }]
    },

And this works Good
见图一
And...When I add more menus...like this
见图二
the collapse doesn't work any more.[Can not disp items in it.Just like menu 2 in the 图二]

Is there any attribute to set so i can solve this?
Or This is a bug of layout:accordion.