problem in updating text

[SUJITH_KJ]

Hi,
I have given my code below. In my program when i press 'w', the avatar walks to the position (0,0,5) and collides with box and prints the text 'santhosh'. When i press 'c' the avatar proceeds to the next position (0,0,15) and collides with box1 and prints the text 'sujith'. but the problem is tat the first text 'santhosh' still remains. I want it to vanish wen the avatar collides with the second box. Pls help me. I am doing a project. Pls help me. Thanks a lot

code:
import viz
import vizact
viz.phys.enable()
viz.setMultiSample(4)
viz.fov(60)
viz.go()
male = viz.addAvatar('vcc_male.cfg')
male.scale(3,3,3)

ground = viz.add('tut_ground.wrl')
ground.collidePlane()

env=viz.add(viz.ENVIRONMENT_MAP,'sky.jpg')
dome = viz.add('skydome.dlc')
dome.texture(env)

box = viz.add('box.wrl',scale=[2,2,2],pos=(0,0,5),color = viz.BLUE)
box.collideBox()
box.disable(viz.DYNAMICS)

box1 = viz.add('box.wrl',scale=[1.5,1.5,1.5],pos=(0,0,15),color = viz.RED)
box1.collideBox()
box1.disable(viz.DYNAMICS)

box2 = viz.add('box.wrl',scale=[1.5,1.5,1.5],pos=(-10,0,0),color = viz.RED)
box2.collideBox()
box2.disable(viz.DYNAMICS)

box3 = viz.add('box.wrl',scale=[1.5,1.5,1.5],pos=(-20,0,0),color = viz.RED)
box3.collideBox()
box3.disable(viz.DYNAMICS)

#textScreen = viz.addText('Press a',parent=viz.ORTHO,pos=[400,500,0],fontSize=50)


rHandBox = viz.add('box.wrl',scale=[1,1,1])
rHandBox.collideBox()
rHandBox.disable(viz.DYNAMICS)
rHandBox.enable(viz.COLLIDE_NOTIFY)
rHandLink = viz.link( male.getBone('Bip01 R Foot') , rHandBox )
#tweak the position of the box to cover the hand
rHandLink.preTrans([0.05,-0.5,0])


def onCollideBegin(g):
textScreen = viz.addText('Press a',parent=viz.ORTHO,pos=[400,500,0],fontSize=50)
textScreen.visible(viz.OFF)
if g.obj1 == rHandBox:
if g.obj2 == box:
box.color(viz.RED)
textScreen.message('santhosh')
textScreen.visible(viz.ON)
#textScreen.visible(viz.OFF)
#new=textScreen.message('somethin new')
#textScreen = viz.addText('Press a',parent=viz.ORTHO,pos=[400,500,0],fontSize=50)
#fun=textScreen.removeParent(textScreen)
#viz.callback(viz.COLLIDE_END_EVENT,onCollideBegin )
if g.obj1 == rHandBox:
if g.obj2 == box1:
box1.color(viz.BLUE)
#textScreen.visible(viz.OFF)
textScreen.message('sujith')
textScreen.visible(viz.ON)
#textScreen1 = viz.addText('Press x',parent=viz.ORTHO,pos=[400,500,0],fontSize=50)
if g.obj1 == rHandBox:
if g.obj2 == box2:
box2.color(viz.BLUE)
textScreen = viz.addText('Press c',parent=viz.ORTHO,pos=[100,0,0],fontSize=50)
if g.obj1 == rHandBox:
if g.obj2 == box3:
box3.color(viz.BLUE)
textScreen = viz.addText('Press r',parent=viz.ORTHO,pos=[400,200,0],fontSize=50)
viz.callback(viz.COLLIDE_BEGIN_EVENT,onCollideBegi n)


def wukavatar():
walk1 = vizact.walkTo([0,0,5])
male.addAction(walk1)
vizact.onkeydown('w',wukavatar)

def wakavatar():
walk2 = vizact.walkTo([0,0,15])
male.addAction(walk2)
vizact.onkeydown('c',wakavatar)