EXTJS4 MVC的时候 出现这个错误 是什么原因啊 求帮助

"NetworkError: 404 Not Found - http://localhost:8080/comManagement/app/view/Viewport.js?_dc=1320986749496"
Viewpo...6749496
An uncaught error was raised with the following data:
ext-all-debug.js (第 4786 行)


classToLoad
"AM.view.Viewport"

loadPath
"app/view/Viewport.js"

loadingType
"async"

msg
"Failed loading 'app/vie...fy that the file exists"

sourceClass
"Ext.Loader"
Failed loading 'app/view/Viewport.js', please verify that the file exists
con.error(msg);
ext-all-debug.js (第 4793 行)
uncaught exception: Failed loading 'app/view/Viewport.js', please verify that the file exists

我跟你遇到同样的问题啊..你解决了没有?