InvalidOperationException: Operation is not valid due to the current state of the object.

Hey guys, I'm trying to get a single sprite from a spritesheet (to use as icons). However, I'm getting an error I havn't encountered before and eventhought alot of the time the errors tell you enough information to fix the error... I have not succeeded. So now I'm asking for your help

Here's my code public void LoadIcons() { // Load all sprites in atlas Sprite[] abilityIconsAtlas = Resources.LoadAll("AbilityIcons");

          print (abilityIconsAtlas.Single (s => s.name == abilityName1));
  
          if (abilityIconsAtlas.Single(s => s.name == abilityName1) != null) {
              abilityIcon1.sprite = abilityIconsAtlas.Single(s => s.name == abilityName1);
          }
          if (abilityIconsAtlas.Single(s => s.name == abilityName2) != null) {
              abilityIcon2.sprite = abilityIconsAtlas.Single(s => s.name == abilityName2);
          }
          if (abilityIconsAtlas.Single(s => s.name == abilityName3) != null) {
              abilityIcon3.sprite = abilityIconsAtlas.Single(s => s.name == abilityName3);
          }
          if (abilityIconsAtlas.Single(s => s.name == abilityName4) != null) {
              abilityIcon4.sprite = abilityIconsAtlas.Single(s => s.name == abilityName4);
          }
      }

Here's my error.

  InvalidOperationException: Operation is not valid due to the current state of the object
  System.Linq.Enumerable.Single[Sprite] (IEnumerable`1 source, System.Func`2 predicate, Fallback fallback)
  System.Linq.Enumerable.Single[Sprite] (IEnumerable`1 source, System.Func`2 predicate)
  Ability_Use.LoadIcons () (at Assets/Scripts/Abilities/Ability_Use.cs:58)
  Ability_Use.Start () (at Assets/Scripts/Abilities/Ability_Use.cs:45)

Thank you for your time, Bazza D Lisk.