daylighting in ecotect/radiance anyone?

i got nothing on the autodesk forums so as a last ditch effort im trying here.
Im exporting my data to radiance, for a Daylight Factor analyis, but the 3D grid option gets greyed out, this has happened before, and i dont remember how i got it to work back then. I have just re-installed ecotect and radiance, but to no avail.

Is this a bug, or a problem others have faced? and is there anyone who has solved it?

 http://forums.autodesk.com/autodesk/attachments/autodesk/356/1454/1...

Thank you for your help.

Regards

Aditya Bhatt