Really appreciate your response.
I could not figure out what's wrong last night, and I even transfer all my source code to my Windows 7 PC and compare to the source I downloaded from the site and still not finding anyway. I ended up deleting the whole project and start from scratch and everything worked again. I am kind of very frustrated using touchpad of my new MAC Pro 17" I just brought,
(may be I am not used to Apple stuff), sometimes, windows just disappear and sometimes file got deleted for no reason. I am not using a USB mouse instead to avoid any unintended error.