Hand's Collision

[Mai]

I am using the following object to touch balloons (as an example)

hand=viz.add('hand.cfg')

to enable the collision I have used the following code:

handballoon = viz.add('balloon.ive',scale=[0.01,0.01,0.01])
handballoon.collideSphere()
handballoon.disable(viz.DYNAMICS)
handballoon.enable(viz.COLLIDE_NOTIFY)
handballoon_link= viz.link( hand , handballoon )
handballoon_link.preTrans([0.07,-0.07,0])
def onCollideBegin(e):
	if e.obj1 == handballoon:
		if e.obj2==balloon:
			print 'Yes Balloon has been touched :',e.obj2
viz.callback(viz.COLLIDE_BEGIN_EVENT,onCollideBegin)

but it does not work
any help would be appreciated