calling a class named by a string

 using UnityEngine;
 using System.Collections;
 using System.Reflection;
 
 public class test : MonoBehaviour {
     // Use this for initialization
     public void CallShipFabric(string ShipScriptName){
     //string is a name of a class/script in the same GameObject
 
     // transform the string into a type
     System.Type ShipScriptType = Types.GetType(ShipScriptName, "UnityEngine");
     
     // instanciate a value of this class(didn't work)
     ShipScriptType ScriptName;
     //link with the good object 
     ScriptName = (ShipScriptType)this.GetComponent(typeof(ShipScriptType));
     //finally able to call a function from the script named by "ShipScriptName"
     ScriptName.CallAFunction();
     }
     void Start () {
     }
     // Update is called once per frame
     void Update () {
     }
 }

Hello everyone, I need to call a function from a script I will only know the name at runtime(well all are already define but i don't know which one will be used because depend on the player choice). I know function they have because they are all children of an abstract class but have different names.

I have try different thing,but nothing seam to work.

thanks.