The variable othertransform of Prefab has not been assigned

Hi everyone

I want to make a GUI button which instantiates a prefab which uses the distance between the player and the prefab itself to modify variables. But when I try to assign the variable othertransform, the transform of the player, the inspector doesn't recognize it. So, how do I assign the variable othertransform from within a script. My player is just the original 3rd Person Controller and it has a tag called Player. These are my scripts: This is the object I want to instantiate

 var mytransform : Transform;
 var othertransform : Transform;
 
 
 function Update (){
 
 if(Vector3.Distance(mytransform.position, othertransform.position) < 100){
 AttackScript.interval = 3;
 MpBasedAttackScript.interval = 5;
 }
 else{
 AttackScript.interval = 5;
 MpBasedAttackScript.interval = 10;
 Destroy (gameObject);
 }
 }

And this is the script I use to generate my button and to instantiate the prefab:

 var instantiatedobject : GameObject;
 var spawnplace : Transform;
 
 function OnGUI () {
 if(GUI.Button(Rect(200,500,100,100),"Buffspring")){
 var instance : GameObject = Instantiate(instantiatedobject, spawnplace.position, spawnplace.rotation);
 }
 }

Please help me solve this problem.