Expected an indented block in nested if statements in Python

Question

I had checked it several times but it still says expected an indented block at if (root.right.left is not None) or (root.right.right is not None)

class Solution(object):
    def sumOfLeftLeaves(self,root):
        if root.val is None:
            return 0
        elif root.left is None and root.right is not None:
            return self.sumOfLeftLeaves(root.right)
        elif root.left is not None and root.right is None:
            return self.sumOfLeftLeaves(root.left)
        elif root.left is not None and root.right is not None:
            if root.left.left is None and root.left.right is None:
                if (root.right.left is not None) or (root.right.right is not None):
                    return root.left.val + self.sumOfLeftLeaves(root.right)
                else:
                    return root.left.val
            else:
                return (self.sumOfLeftLeaves(root.left)+self.sumOfLeftLeaves(root.right))
        else:
            return 0

Help please.