Hello Patrick, I might not be an expert in this, but I think you check several things. I would advise you to train a child who can walk to the potty by herself. If they take simple instructions too, it is easy to instruct them to use the potty. Some people use gifts for each successful attempt use the potty by the child. Check if the child shows some discomfort after they soiled the diaper or a wet it. She may be ready for the alternative.
Good luck.