[ODE] connect a body to the static environment

[3emeType]

Hi, I'm new to ODE.
In the doc I see :
"How do I connect a body to the static environment with a joint?
Use dJointAttach with arguments (body,0) or (0,body)."

ok but when I connect one of the bodies of my ragdoll to the static
environment, nothing happens. I thought connect a body to the static
environment was hanging it up at the position of the connection, like
here : http://blogsimages.skynet.be/images/000/341/304_pendu(gray-H)web_petit.jpg,
or in this shockwave demo :
http://director-online.com/havok/demos/demo-ragdoll2-old.html.
But my ragdoll just fall to the ground :(

Do you have any solution to hang up a ragdoll by its head or by a part
of its body ?