Disabled = true doesn't work

[unemployment]

once I toggle the select all button on it enabled the another button, but once I toggle the select all button often it doesn't disable my other button.

 

function selectall (pm) {
var messages= document.getElementById('pm');
 if (checked == false)
          {
           checked = true;
           document.getElementById('multiple_action').disabled = 'enabled';
	   document.getElementById('drop_button').setAttribute("class", "drop_button");
          }
        else
          {
          checked = false;
          document.getElementById('multiple_action').disabled = true;
          }
for (var i =0; i < messages.elements.length; i++) 
{
 messages.elements[i].checked = checked;
}
}
checked=false;

[sunfighter]

What other button? You should show us what you mean.