text area value within window

I am unable to get the value of text area that is part of oblect attached to window. Window is displayed. User types some text to text area. I am using $(‘textAreaId’).value and getting “” instead of typed text.

Please advise.

Is content attached to the window directly ( some html object from the same page ) or you are using attachURL method?
In second case , content will be loaded in separate iframe and not accessible by ID.