Problems with sit on target

What do I wrong? I think I oversee something. I have put this in a cube. I always get an empty key returned. Any tips?


default
{

changed(integer change)
{
llSay(0, "Changed entry";

if (change & CHANGED_LINK)
{
llSay(0, "Avatar seat changed";

key agent = llAvatarOnSitTarget();

if (agent)
{
llSay(0, "Seated";
}

else
{
llSay(0, "Not seated";
}
}
}

}

For that function to work, you first have to have a sit target defined via llSitTarget, and the vector has to be something other than ZERO_VECTOR.

That did the job. Thanks Talarus Luan.