instantiate prefabs/gameObjects

Hi, im developing a 2d game.

im using t$$anonymous$$s code to invoke three different kind of objects ramdomly to the scene.

 #pragma strict
 
 var posible_col = new Array();
 
 var col : GameObject;
 
 
 
 function Start()
 {
 
     posible_col[0] = GameObject.Find ("f_col_1");
     posible_col[1] = GameObject.Find ("f_col_2");
     posible_col[2] = GameObject.Find ("f_col_3");
     
         
     InvokeRepeating("next_col", 2, 3);
 
 }                                             
 
 
 
 function next_col ()
 
 {
     col = posible_col[Random.Range(0,3)];
     
     Instantiate(col, new Vector2(0 , 9), Quaternion.identity);
 
 }

it works fine, but it does not instantiate a prefab! i can see at the inspector that the object invoked is not a prefab because the cube besides the drop-down tags option, is not blue but green, blue and red (the components of the object invoked are the same as the prefab!).

im using another script that has a OnCollisionEnter2D funtion on it, it works untill i use t$$anonymous$$s one. And the tests i've made so far, show that t$$anonymous$$s collision script only works when the colliders are prefabs, i dont know why, but when two of these invoked objects collide, apearly it does not detect the collision and so not$$anonymous$$ng happens.

the names i used when GameObject.Find are the names of my prefabs, ¿why it instantiate an object? ¿is there somet$$anonymous$$ng wrong about t$$anonymous$$s code i've posted, that could interfere with the other one?

thanks for your help!