xp cost repair and floating xp orb

When I tried collecting a experience orb, it won't get collected. Also, when I tried repairing a bow by combining it with another bow on an anvil, it said it was too expensive. I was on survival mode so i tried using the give experience command until I had reached over 10000 experience. Still it was too expensive so when I did the same thing in creative mode, it said it costed me about 120 or 65 experience.