QtNetwork: No such file or directory

要準備跑Qt的其中一個範例程式，socket結果出現以下問題~
QtNetwork: No such file or directory

原來要在.pro檔案中加以下內容
Configuring the Build Process

Applications that use Qt's networking classes need to be configured to be built against the QtNetwork module. The following declaration in a qmake project file ensures that an application is compiled and linked appropriately:


QT += network