error CS1061 and error CS0117 scripting InputField

I'm trying to create an Input Field to send commands to a simple AI. I'm getting this error:

Assets/Scripts/InputController.cs(15,23): error CS1061: Type 'string' does not contain a definition for 'text' and no extension method 'text' of type 'string' could be found (are you missing a using directive or an assembly reference?)

From this following script:

 using UnityEngine;
 using UnityEngine.UI;
 using System.Collections;
 
 public class InputController : MonoBehaviour {
 
     private InputField input;
 
     void Awake(){
         input = GameObject.Find ("InputField").GetComponent<InputField>();
     }
 
     public void GetInput(string input){
         Debug.Log (input);
         input.text = "";
     }
 }

FYI: The 'text' parameter in the input component is highlighted in red in the MonoDevelop:

         public void GetInput(string input){
             Debug.Log (input);
             input.text = "";
         }

When I hover over it in the MonoDevelop I get the following error in a balloon message:

Error CS0117: 'System.String' does not contain a definition for 'text'

• I test this in a plain new project and scene and it works.