Can't Get Month Year From Variable Using Date()

I have a very simple question about date(). I am using date('l, F d, Y'); to show Tuesday, August 22, 2006. But now when I am trying to display just Month - Year i.e (August - 2006) from variable, Its not coming through and displaying January - 1970.

Code: I have done date("F - Y", $entry_date) for this. Can any one just point me out or suggest where I am wrong here?