I want the labels on Y-axis to be start from zero.
What should I do?

Here's what I've done to get the zero included on the axis:

' use a range axis view to set the actual range of values you want displayed.
chart.Axis(StandardAxis.PrimaryY).View = New NRangeAxisView(New NRange1DD(0, yMax))

' use a scale configurator to turn off the tick rounding at the axis minimum
Dim valueScale As NLinearScaleConfigurator = New NLinearScaleConfigurator()
valueScale.RoundToTickMin = False
chart.Axis(StandardAxis.PrimaryY).ScaleConfigurator = valueScale

This has worked for me. I'd be happy to know if there is a "better" way.

Regards

Mike