How to make the x-Bottom scale fixed.

[Tavit]

Hi jacek i even tried what you asked me to myPlot->replot(), But this does't seem to work there is no change in the curve it just plots till 60 and stays there it does't clear or replot.When i use myPlot->clear it plots till 60 and clears there but the next curve is not plotted.The qwt plot widget stays blank.
Pls tell me what is the mistake i am doing. jacek


Thank you