style sheets

[TheKedge]

hello all,
what's wrong here .. ?

btnOnOff = new QPushButton("start/stop");
btnOnOff->setCheckable(true);
qApp->setStyleSheet("#btnOnOff{color:green}");//this has no effect
qApp->setStyleSheet("QPushButton{color:green}");//this colours all QPushButtons (as excpected

btnOnOff = new QPushButton("start/stop");
btnOnOff->setCheckable(true);
qApp->setStyleSheet("#btnOnOff{color:green}");//this has no effect
qApp->setStyleSheet("QPushButton{color:green}");//this colours all QPushButtons (as excpected

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I may have missed something silly. Why is the first setStyleSheet() ignored? Do I have to tell sombody about the name 'btnOnOff?

thanks
K