Undefined symbols while linking with QWT 6.0.1

My environment is MAC OS X 10.5.8, Qt 4.7.3, Qwt 6.0.1 (installed as in manual and linked via qwt.prf). While building my application and some examples (bode.pro) I got error message:

Undefined symbols:
"QwtPlot::setCanvasBackground(QBrush const&)", referenced from:
CSpectrumView::CSpectrumView(QWidget*)in SpectrumView.o
CSpectrumView::CSpectrumView(QWidget*)in SpectrumView.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

Function setCanvasBackground(QBrush const&) is declared in QwtPlot class but it seems to be absent in library. Did I build and install library wrong?