I check out the latest qwt (Release 6.0) from the svn server, and compiling the codes with default configures. However, I get the fellowing link errors:

...
compiling .\qwt_designer_plugin.cpp .\qwt_designer_plotdialog.cpp
qwt_designer_plugin.cpp
qwt_designer_plotdialog.cpp
Generating Code...
compiling moc\moc_qwt_designer_plugin.cpp moc\moc_qwt_designer_plotdialog.cpp
moc_qwt_designer_plugin.cpp
moc_qwt_designer_plotdialog.cpp
Generating Code...
compiling resources\qrc_qwt_designer_plugin.cpp
qrc_qwt_designer_plugin.cpp
linking plugins\designer\qwt_designer_plugin6.dll
Creating library plugins\designer\qwt_designer_plugin6.lib and object plugins
\designer\qwt_designer_plugin6.exp
qwt_designer_plugin.obj : error LNK2001: unresolved external symbol "public: vir
tual void __thiscall QwtPlot::drawItems(class QPainter *,class QRectF const &,cl
ass QwtScaleMap const * const)const " (?drawItems@QwtPlot@@UBEXPAVQPainter@@ABVQ
RectF@@QBVQwtScaleMap@@@Z)
qwt_designer_plugin.obj : error LNK2001: unresolved external symbol "public: vir
tual void __thiscall QwtThermo::setValue(double)" (?setValue@QwtThermo@@UAEXN@Z)

plugins\designer\qwt_designer_plugin6.dll : fatal error LNK1120: 2 unresolved ex
ternals
NMAKE : fatal error U1077: 'echo' : return code '0x460'
Stop.
NMAKE : fatal error U1077: '"D:\Program Files\Microsoft Visual Studio 9.0\VC\BIN
\nmake.exe"' : return code '0x2'
Stop.
NMAKE : fatal error U1077: 'cd' : return code '0x2'
Stop.

E:\QT\qwt>

My platform is Win7+VS2008+Qt4.6.0, Anybody know what's the problem?