Help with if else statements

I am trying to create a rezzer that rez's and object only if a prior version of it doesn't exist.

I figured that I could use a listen and an if / else condition but it does not seem to work. The rezzer is shouting and responds when the object is in world. (ie it syas it can't rez and doesn't)

but it does not seem to execute the else part if the object doesn't exist.

this is the script

default {
    state_entry()
    {llListen(251175,"","","");
}
    touch_start(integer num_detected)   
    {    
       
    llShout(251175,"do you exist");}

    listen(integer channel, string name, key id, string message)
{
    if (message == "yups")
    {
        llSay(0, "Please wait for the Line to be cleared");
}

else  
 {
        llSay(0,"working");
        llRezObject("Zip Line ring", llGetLocalPos() + <0,-0.8,0>, <0,0,0>,llGetRot(), 42);
}

    }
}

any help please as the wiki sdoes not seem much use

Not sure I understand the overall design here, but if the "else" clause in the listen() is supposed to happen when there was no message, that's not gonna work. The listen() event only happens when there's a message. If that's the idea, a timer event would be a sensible trigger. (If that's not the idea, then sorry for the confusion.)

That's exactly the idea I need to make the rez event happen if there is no message. So I would create a timer that rezes at the end but kill the timer if there is a message?

so here is the working script just in case anyone else want it

default {
    state_entry()
    {llListen(251175,"","","");
}
    touch_start(integer num_detected)   
    {    
       llSetTimerEvent(2);
    llShout(251175,"do you exist");}

    listen(integer channel, string name, key id, string message)
{
    if (message == "yups")
    {
        llSay(0, "Please wait for the Line to be cleared");
        llResetScript();
}
}
timer()
{
        llRezObject("Zip Line ring", llGetLocalPos() + <0,-0.8,0>, <0,0,0>,llGetRot(), 42);
llResetScript();
}
    }

you can also use llRegionSay instead of llShout, and the entire sim is covered then.

1. I don't think a script will listen to itself.
2. Whu use llResetScript() instead of a new llSetTimerEvent(2) ?

Also, if you expect the object to be within 96m, you can use a sensor (96m is the limit of llSensor). Then you can have positive confirmation either way via the sensor and no_sensor events.

Lyn the script is speaking to another object to see if it already exists. If it doesn't it will rez the object. I only want ones existing within chat range at a time. Thats the main reason I have used the llShout rather than llRegionSay.

The llResetScript() is just to stop the timer so only one object gets rezzed and the script is back to it's ready state. Does that make much difference in terms of lag from setting a new timer. I figured it was the easiest way to quit the timer from what it says on the wiki.

Mereille I hadn't thought of using a sensor instead, I guess that would reduce lag but as it's only a periodical use of chat (as in when the user touches) and the object doing the listen is temporary I figured it wouldn't matter too much. I guess the problem is the listen in the rezzer waiting for confirmation. I will look into replacing that section of code thanks for the pointer.