Hello everyone.I'm now having a difficult time on xStream 10 intergration with vray in MAX2012

I have a vraysun in my max scene.When I load the xStream plugin,the XS will automatically creates a ground,a camera and a sun light.I think the sunlight should be matched to the vraysun,so I can only adjust the vraysun and get the sunlight right.But sometimes somehow I'll lost the directional light(the vraysun is still on)

look at below.The 1st image has both environment light and directional light,the bottom image has no directional light(sunlight).No matter how I turn on/off the vray sun it still doesn't work.But sometimes somehow it just appears right again:( 

Is it because the intergration is not stable?or can I fix it?(I'm sure I didn't change the light balance in vue atmo editor to all ambient)

 

The second question is,when I use the Vue sky and atmo,how should I set the Vray::Environment?Turon off all the settings?or use no map?or use Vraysky map?

 

sorry for my english,hope if anybody could help me,thanks!