Why don't any of these BST methods work?

Ok so in my binary search tree I made a bunch of methods but I'm currently testing 2 of them. One of them inserts an item into the tree:

public void insert(String word) { //calls the insert method
    root=insertItem(root, word);
}


protected TreeNode insertItem(TreeNode r, String word) { //inserts an item x into the tree
    if(r==null){
        r = new TreeNode(new WordRefs(word));
        r.left = null;
        r.right = null;
    }
    else if(word.compareTo(r.item.getWord()) < 0){
        r.left = insertItem(r.left, word);
    } else if (word.compareTo(r.item.getWord()) > 0){
        r.left = insertItem(r.right, word);
    }
    return r;
}

The other one deletes an item:

public void delete(String word) { //calls the delete method
    root = deleteItem(root, word);
}


protected TreeNode deleteItem(TreeNode r, String word) { //deletes an item x from the BST 
    if (r == null){
        return r;
    }
    if(word.compareTo(r.item.getWord()) < 0){
        r.left = deleteItem(r.left, word);
    } else if (word.compareTo(r.item.getWord()) > 0){
        r.right = deleteItem(r.right, word);
    } else if(r.left != null && r.right != null){
        return deleteItem(r, word);
        }
    return r;
}

And here is the code that tests these methods

public static void main(String args[]) { //the tests are in the main method
    BSTRefBased t;
    AbstractBinaryTree tt;
    int i;
    boolean result;
    String message;

    message = "Test 1: inserting 'word1' -- "; //tests the insert method first
    t = new BSTRefBased();
    try {
        t.insert("word1");
        result = t.getRootItem().getWord().equals("word1");
    } catch (Exception e) {
        result = false;
    }
    System.out.println(message + (result ? "passed" : "FAILED"));

    message = "Test 2: inserting 'word1', 'word2', 'word3' -- ";
    t = new BSTRefBased();
    try {
        t.insert("word1");
        t.insert("word2");
        t.insert("word3");
        result = t.getRootItem().getWord().equals("word1");
        tt = t.detachLeftSubtree();
        result &= tt.getRootItem().getWord().equals("word2");
        tt = t.detachRightSubtree();
        result &= tt.getRootItem().getWord().equals("word3");
    } catch (Exception e) {
        result = false;
    }
    System.out.println(message + (result ? "passed" : "FAILED"));

    message = "Test 3: deleting 'word1' -- "; //it then tests the delete method (note I keep getting failed for this one)
    t = new BSTRefBased();
    try {
        t.delete("word1");
        result = t.getRootItem().getWord().equals(null);
    } catch (Exception e) {
        result = false;
    }
    System.out.println(message + (result ? "passed" : "FAILED"));

            message = "Test 4: deleting 'word2' 'word3' -- ";
    t = new BSTRefBased();
    try {
        t.delete("word2");
        t.delete("word3");
        result = t.getRootItem().getWord().equals(null);
        tt = t.detachLeftSubtree();
        result &= tt.getRootItem().getWord().equals(null);
    } catch (Exception e) {
        result = false;
    }
    System.out.println(message + (result ? "passed" : "FAILED"));
}

For my output it says test 1 passed but test 2, 3, and 4 all failed. So why did test 2, 3, and 4 fail?