While the CBS color broadcasting schedule gradually expanded to twelve hours per week (but never into prime time), and the color network expanded to eleven affiliates as far west as Chicago, its commercial success was doomed by the lack of color receivers necessary to watch the programs, the refusal of television manufacturers to create adapter mechanisms for their existing black-and-white sets, and the unwillingness of advertisers to sponsor broadcasts seen by almost no one. CBS had bought a television manufacturer in April, and in September 1951, production began on the only CBS-Columbia color television model, with the first color sets reaching retail stores on September 28. However, it was too little, too late. Only 200 sets had been shipped, and only 100 sold, when CBS discontinued its color television system on October 20, 1951, ostensibly by request of the National Production Authority for the duration of the Korean War, and bought back all the CBS color sets it could to prevent lawsuits by disappointed customers. RCA chairman David Sarnoff later charged that the NPA's order had come "out of a situation artificially created by one company to solve its own perplexing problems" because CBS had been unsuccessful in its color venture.