building error: Unknown module (s) in QT: webkitwidgets

Hi guys, I downloaded “qt-everywhere-opensource-src-5.0.2” and built it with msvc10 to D:\qt-5.0.2-msvc10-bin. And then I ran “Perl qtwebkit\Tools\Scripts\build-webkit” to build QtWebkit. I got the building result files under qtwebkit\WebKitBuild\Release. And then, I copied qtwebkit\WebKitBuild\Release\include and qtwebkit\WebKitBuild\Release\lib to D:\qt-5.0.2-msvc10-bin. Now I can build and run the example “network\http”. But when I built the demo “webkitwidgets\previewer” I got the error: “Unknown module (s) in QT: webkitwidgets”. I checked the file previewer.pro, there is the code line “QT += webkitwidgets network widgets”. How can I fix this problem? thanks.