Walgreens never told federal or state authorities that one of its pharmacists had made a mistake on a prescription that led to devastating brain damage in a suburban Chicago infant. Because it didn’t have to. Neither the federal government nor 46 of the 50 states have any law requiring that drug stores report prescription errors, even in cases involving serious injury or death. See Pharmacy Errors in Pictures. While some fear there is an unreported epidemic of pharmacy errors, there are no reliable figures to gauge the scope of the problem. And that’s the way the industry seems to like it. "I don’t think it should be publicized," said Mary Ann Wagner, the senior vice president of the National Association of Chain Drug Stores, in an interview to be broadcast Friday on "20/20." Click Here for Full Blotter Coverage. She says the industry fears the public won’t understand the difference between minor and major errors, and that the figures could be used to punish drug stores. In the suburban Chicago case, the pharmacist mistakenly put a medicine for adult diabetes in filling a Phenobarbital prescription for seven-month-old Alexandra Gehrke. Alexandra’s mother, Tracey Gehrke, says the medicine was intended as a precaution against seizures in her prematurely-born daughter but actually triggered severe seizures. "I was poisoning my baby, and I didn’t know it," she told "20/20." A jury ordered Walgreens to pay the family $21 million in damages, but the Gehrkes say neither the company nor the pharmacist ever offered an apology for a mistake that forever altered their daughter’s life. Alexandra cannot walk, talk or feed herself, although she is expected to have a normal life expectancy. "You hurt people, and you don’t apologize?" Tracey Gehrke asked. The pharmacist who admitted responsibility for the error, William Zaeske, continues to work at Walgreens and is now a pharmacy manager at another store near the one where the prescription error happened. Zaeske declined to answer questions from "20/20" about how the error occurred. In a statement, Walgreens said, "We deeply regret the few errors that have occurred among the more than 500 million prescriptions we fill each year at our 5,600 pharmacies." As the country’s biggest pharmacy chain, Walgreens recently reported record profits. It says it has invested nearly $1 billion in "redundant pharmacy safety systems" and training over the last 10 years. For the full investigation, watch "20/20" Friday at 10 p.m. EDT.