I can't make my sub class inherit from my base class [Mac + MonoDevelop]

Im currently building some UI elements in Unity, and I have different scripts on various elements in the UI. I have the following classes in two separate files:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class loadTxt : MonoBehaviour {
 
 
     public string textFile = "text";
     string textContent;
 
     List<string> productList;
     private string[] productArray;
 
 
     void Start () {
 
         TextAsset txtAsset = (TextAsset)Resources.Load (textFile);
         textContent = txtAsset.text;
 
         productArray = textContent.Split (';');
 
         productList = new List<string> ();
 
         for (int i = 0; i < productArray.Length; i++) {
             productList.Add (productArray [i]);
         }
     
     }
 
     void RemoveFromList(int index) {
         productList.RemoveAt (index);
     }
 
     public string TextContent {
         get { return this.textContent;}
         set    { textContent = value; }
 
     }
     
 
     void OnGUI () {
         for (int i = 0; i < productList.Count; i++) {
             GUILayout.Label (productList[i]);
         }
 
     }
 }
 
 class onClickRemove : loadTxt {
 
     textContent = "new_value";
 
     public void onClick() {
         TextContent = "other_value";
     }
 }

For some reason I can't inherit any variables or functions in my sub class "onClickRemove" from my base class "loadTxt". If I type in a change the value of the variable "textContent" in my sub class, the program does not autocomplete the function name and if I type in the change anyway I get an error saying the variable does not belong in that content, which basically means the sub class has not inherited the values from its base class.

What am I missing to get it to work, Ive searched to find an explanation to this problem but no fix have worked so far.