SharePoint Ribbon custom button "enablescript"

Hi,

I want to set  permission for  all selected items in library.

I 've added custom button   to ribbon.

My custom button{  find all selected items and redirect to "mypage.aspx?ids=12,25,45" } .

In them there is no problem....

But..

if curentuser  does not have  full control  permissions  then  mybutton must be disable..

EnableScript not working:((

I 'have tried this and like this  examples.

I inserted alert('') between rows..

 and this row not working.

http://social.technet.microsoft.com/Forums/sharepoint/en-US/f21ad6b1-445a-497d-a286-d3ba8c2928a6/how-to-get-the-current-user-permission-level-on-a-list-item-with-ecmascript