I have to second what monkris is saying. I am having this issue as well. This seems to apply to bump maps too. Both normal and bump maps don't show any effect after the vaule 1 . Neither do they affect the lighting in anyway.
In cycles or 3dsmax, this is not an issue. With 3dsmax, corona bump and normal work correctly even when using high vaules.
@burnin Even from the image u have posted, the bump at 5cm doesn't seem to affect the lighting.
Is there anyway this can be looked into. Unfortunately, I am using Corona right now, and I have gone too far to switch in the project.
Thanks :-)