URGENT - Cannot be serialized because it does not have a default public constructor....

Hi there,

I am trying to make a game and need a score system.

The error i get is: InvalidOperationException: ScoreData cannot be serialized because it does not have a default public constructor

And my code is:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using System.Xml;
 using System.Xml.Serialization;
 using System.IO;
 using UnityEngine.UI;
 using System;
 
 public class scoresSaver : MonoBehaviour {
 
     public static ScoreList scorelist;
 
     public GameObject HighScoreText;
 
     public Transform parent;
 
     public GameObject text;
 
     public static List<ScoreData> scores = new List<ScoreData>();
 
     void Start()
     {
         LoadScores();
     }
 
     public static void AddScore(string nameIn, int scoreIn)
     {
         XmlSerializer serializer = new XmlSerializer(typeof(ScoreList));
         FileStream stream = new FileStream(Application.dataPath + "/StreamingAssets/highscores.xml", FileMode.Open);
         scorelist = serializer.Deserialize(stream) as ScoreList;
         foreach (ScoreData score in scorelist.scores)
         {
             scores.Add(score);
         }
         scores.Add(new ScoreData(nameIn, scoreIn));
     }
 
     public void LoadScores()
     {
         XmlSerializer serializer2 = new XmlSerializer(typeof(ScoreList));
         FileStream stream2 = new FileStream(Application.dataPath + "/StreamingAssets/highscores.xml", FileMode.Open);
         scorelist = serializer2.Deserialize(stream2) as ScoreList;
         foreach (ScoreData score in scorelist.scores)
         {
             scores.Add(score);
         }
         scores.Sort();
         scores.Reverse();
         stream2.Close();
 
         foreach (ScoreData score in scores)
         {
             print(score.Name);
             print(score.Score);
             text = Instantiate(HighScoreText);
             
             text.transform.SetParent(parent);
             text.GetComponent<Text>().text = score.Name + ": " + score.Score;        
         }
     }
 
 }
 
 [System.Serializable]
 public class ScoreData : IComparable<ScoreData>
 {
     public string Name;
     public int Score;
 
     public ScoreData(string newName, int newScore)
     {
         Name = newName;
         Score = newScore;
     }
 
     public int CompareTo(ScoreData other)
     {
         if (this.Score > other.Score)
             return 1;
         else if (this.Score < other.Score)
             return -1;
         else
             return 0;
     }
 }
 
 [System.Serializable]
 public class ScoreList
 {
     public List<ScoreData> scores = new List<ScoreData>();
 }

I hope someone can help.

Many Thanks