Vray dome light not working as expected

[vuegroup]

I am having trouble with the vray dome light not working as IBL.
I am hooking a maya file node with a sunny day, blue sky HDRI to the dome tex slot.
When I render I get what looks like sky fill. I dont get any high intensity lighting from the bright sun areas of the image.
It is as though it was an 8 bit image not an HDRI which it proves to be on checking in photoshop.
In fact I have tried a pile of HDRI images all with the same result a general fill light but no key light from the bright areas.
I have looked at the tutorial with the clock and cant seem to see what I am doing wrong.
What is the trick to get this to work, what am I missing?

I am using maya 2012 and vray 2.20.01

Thanks

[tashko.zashev]

Hello,
Note that your HDR images need to be with good dynamics to produce high contrast render and sharper shadows. Also you can try to use one with smaller bright spot and high intensity value for the Dome light. If your HDR images are with low dynamic values you can use an approach with combination of V-Ray Dome light with HDR texture as fill light and V-Ray Sun as key light.