asp HyperLink return false return true:can't work properly

 function Addcontainer(id)//invoked by “集装箱信息” id HyperLink_container_info
        {           
           var mywin=window.showModalDialog('view_container.aspx?jobseid='+id,window,'status:Modeless;edge:raised;unadorned:no;scroll=no;resizable:yes;center=yes;help:no;dialog690px;dialogheight:400px')
           alert(mywin);
           if(mywin == '')
           {
               document.getElementById('btnRefresh').click();
           }
           
           if(mywin == 'ok')
           {return true;//如果HyperLink_container_info是个asp Hyperlink 这里会在页面上显示“true”
             　//document.getElementById('btnRefresh').click();
           }
        }