display a plot point by point

[oswalidos]

hello
i finally downloaded qwt from svn and everything is ok (Qt 4.5 ,qwt 5.3.0,windows xp)
now i need to display a plot point by point ,so i tried to create a retard with Qtimer ,but it doesn't work !

no execution or complilation errors but i haven't the result i'm expecting
it's my first program with qwt ,i'm following the pdf given with qwt 5.1.1
the documentation for qwt 5.1.1 still useful ?

thanks in advance