Resource.Load Prefab not working on a fetched string

I am trying to instantiate a prefab with Resource.Load as its parameter but it gives “ArgumentException: The thing you want to instantiate is null.”

I saw almost all questions on this topic but in my case i feel the problem is a bit different.

I have 3 prefabs named Tree101, Tree102, and Tree103 namely in my Resources folder which is in my assets folder.

My Instantiate code is:
GameObject treePut = (GameObject)Instantiate(Resources.Load(treeToPut,typeof(GameObject)));

I also tried : GameObject treePut = (GameObject)Instantiate(Resources.Load(treeToPut));

where treeToPut is string variable which gets input from a text file.
I used Debug.Log to check if it returning right string name and it does give either Tree101,Tree102 or Tree103.

Now I checked treeToPut = "Tree101" and my code works without error.

My treeToPut code is:`

string treeToPut = pickTree();

public string pickTree()

    string treeName;
    if (leveldata.dataLoaded)
        int totalTrees = leveldata.treePosDB.Length;
        int pickedTree = Random.Range(1, totalTrees);
        treeName = leveldata.treePosDB[pickedTree].treeName;
        treeName = pickTree();
    return treeName;

Debug.Log gives the same values as the prefab names so i dont know what im doing wrong, please if anyone can solve my doubt…

First i would recommend to split the calls up. The compiler will create temporary variables anyway.

GameObject prefab = Resources.Load(treeToPut) as GameObject;
GameObject treePut = Instantiate( prefab ) as GameObject;

You will most likely see that the prefab is null as the error message says. Make sure that it isn’t in a subfolder or that the subfolder is in the name (eg. “trees/tree101”)

When you set the treeToPut to “tree101” and it works, then maybe you got control characters in the tree names from parsing the text file?