sit script

The following sit script only seems to put the avatar at the right orientation one third of the time. What am I going wrong?

default
{
state_entry()
{
vector eul = <0,90,180>; //90 degrees around the z-axis, in Euler form
eul *= DEG_TO_RAD; //convert to radians
rotation quat = llEuler2Rot(eul); //convert to quaternion
llSitTarget(<0.0, 0.0, 1.3>, quat);
}
touch_start(integer total_number)
{
llSay(0, "Right click me and choose 'Sit Here' to sit down";
}
}