Ball Pythons are not sight hunters having evolved to hunt mostly in dark rat burrows and so forth. The strikes are not likely true misses but more likely defensive "get away from me rat" type strikes.

How big/old is this snake? A 40 gallon is a lot of open glass for these shy snakes. Where is the tank in your home? (quiet room, busy room, etc.) How long have you had this snake and what is her feeding history prior to you owning her? What is your feeding routine so far? Are you handling the snake at all right now?