Trouble compiling source from Subversion

It seems that recently MuseScore has changed to requiring Qt4.6, which I have installed but I am still unable to compile. (I am running Ubuntu 9.10, but I installed Qt from source) The error I get seems to occur right at the end during the linking stage so I presume it has something to do with my non-package install of Qt.

Linking CXX executable mscore
CMakeFiles/mscore.dir/plugins.cpp.o: In function `MuseScore::pluginTriggered(int)':
/home/stuart/svn/mscore/mscore/mscore/plugins.cpp:271: undefined reference to `QScriptEngineDebugger::action(QScriptEngineDebugger::DebuggerAction) const'
/home/stuart/svn/mscore/mscore/mscore/plugins.cpp:268: undefined reference to `QScriptEngineDebugger::QScriptEngineDebugger(QObject*)'
/home/stuart/svn/mscore/mscore/mscore/plugins.cpp:269: undefined reference to `QScriptEngineDebugger::attachTo(QScriptEngine*)'
collect2: ld returned 1 exit status
make[3]: *** [mscore/mscore] Error 1
make[3]: Leaving directory `/home/stuart/svn/mscore/build'
make[2]: *** [mscore/CMakeFiles/mscore.dir/all] Error 2

Also, the correct make seems to be being used:

stuart@stuart-lt:~/svn/mscore$ which qmake
/usr/local/Trolltech/Qt-4.6.0/bin/qmake

Any ideas?

Thanks,
Stuart