[Closed] intersectray with a BBox of a group

This piece of code works if mygroundObj is geometry, but myrays gives undefined if mygroundObj is a group.

rayPos = [obj.pos.x, obj.pos.y, highestPoint]
myray = intersectray mygroundObj (ray rayPos [0,0,-1])

Is it possible to use intersectray with a group (or with its BBox)? If yes, please help!