[web2py] sorry I don't understand URL

[Stef Mientki]

 hello,

I'm trying to call a service from menu buttons,
and I read somewhere in the manual, you should always use URL()

Now this works:
  LSB_Menu.append ( [ 'Stef3',"call/run/Set_Page/77" ])

But the following don't (while printing the URL result, looks ok), why ??
  #LSB_Menu.append ( [ 'Stef4',URL("call", "run", "Set_Page", args="77" ) ])
  #LSB_Menu.append ( [ 'Stef5',URL("call", "run", "Set_Page", vars="77" ) ])
  #LSB_Menu.append ( [ 'Stef5',URL("call", "run", "Set_Page", "77" )])

# this is the service
from gluon.tools import Service
service = Service(globals())
def call():
  return service()
@service.run
def Set_Page(Nr):
  return dict ( m='aap',b=99,c=Nr)

thanks,
Stef Mientki