Problem With Viewport background

Masters,

I have a strange problem with manipulating bacground in viewport. I put a an hdri map in the environment tab as my model background. However, my vray physical camera cannot render it, but when i replace the camere with a target camera the background appears upon render.When i press "ALT B" to access my viewport background, i sometimes get a message of "no driver to handle given file". Im using max design 2011, vray sp5.Please help po.