close Doc using Javascript

Hi folks,

i have a custom form and we use javascript to save and close the PDF file. Eveything works fine if  use save or close button on the form. If  we make any changes and  click on the 'X' button of Adobe reader which ask a conformation box and if i click on cancel and then if i click on custom close button, doc is not closing. Im using below  javascript code to close 

this.closeDoc(true);

if we directly clicked on close button without clicking 'x' button everything works fine. Any inputs really appreciated.