OPRAH WINFREY routinely reminds her nearly nine million followers on Twitter to tune into her one-year-old channel, OWN, and chats along with viewers on premiere nights. Those informal messages create a direct connection between one of the most famous women in the world and her fans.

But on Sunday night, when she used that powerful online megaphone to make what seemed to be a simple plea, Ms. Winfrey broke a rule that the Nielsen ratings company rarely has to enforce. “Every 1 who can please turn to OWN especially if u have a Neilsen box,” she wrote on Twitter just as a new episode of her interview show, “Oprah’s Next Chapter,” began.

What seemed to most Twitter users to be a simple, if misspelled and desperate-sounding, call to watch a struggling channel was seen by Nielsen as a potentially serious violation of its policy. Nielsen measures the television viewership of a sample of roughly 25,000 households across the United States, and it works hard to ensure that the sample is not coerced to watch specific shows or channels.

After officials at OWN and Nielsen corresponded on Monday morning, Ms. Winfrey removed the Twitter post at the ratings company’s request. “I intended no harm and apologize for the reference,” she said in a statement.