Answer:
The prime reason for the treatment to get failed that though she has been suffering from anemia, it does not prove that she is low in iron. Providing her treatment with iron would possibly give her more than she required in her body.
The actual reason for anemia in the given case would be the lack of function of the beta proteins in the hemoglobin. This can be found out by looking through the family history, that is, if the family had anemia then the condition could be inherited, and it can be determined via blood examinations.