One object pushes another

I'm having a little trouble understanding how to get this script to do what I want. Basically, I want one object to push another.

Imagine a ball sitting on a trampoline. The ball is physical. The trampoline has this script inside:

float force_amount = 1.5;

default {
    touch_start( integer num_d ) {
        llSensor( "Ball", NULL_KEY, ACTIVE, 1, PI );
    }
    
    no_sensor() {
        llOwnerSay( "no ball" );
    }
    
    sensor( integer num_d ) {
        llOwnerSay( "push ball" );
        llPushObject(llDetectedKey(0), force_amount*llRot2Up(llGetRot()), ZERO_VECTOR, FALSE);
    }
}

This script works when the ball is already in motion. If you click the trampoline, it will push the ball. However, I want it to also push balls which are lieing still at the moment. So... I tried substitute "PASSIVE" where it says "ACTIVE" and the sensor finds the ball. But the push doesn't seem to work.

Is there some restriction using llPushObject on an object that has come to standstill?

Pushobject does have some restrictions, I would try having the balls themselves use applyimpulse at an upward angle when they collide with the trampoline.