Error: Persistent store migration failed, missing source managed object model.

I'm getting the following message error:

Error: Persistent store migration failed, missing source managed object model.

I've copied a xCode project from the company mac to my mac (same configuration: Snow Leopard, XCode 3.2

I've cleaned the project, 
deleted the build folder in finder, 
deleted Library/Application support/myApp folder
deleted Library/Prefere开发者_C百科nces/MyApp...plist file

I still get the error. What's wrong with it ? thanks

Quit the XCode Completely and reopen Xcode