[Warcaptain]

its triggerclient("gui",weaponname,param1,param2);

Your problem is that you are expecting it to work like triggeraction and it does not.

It will be:

NPC Code:

---

function onActionServerSide(){

  triggerclient("gui",this.name,"dothis","forme");

}

//#CLIENTSIDE

function onCreated() triggerserver("gui",this.name,"");

function onActionClientSide(){

  switch (params[0]){

    case "dothis":

      echo(params[1]);  

  }

}

---