*Oprah Winfrey has nine million followers on Twitter, and regularly tweets out requests to tune into her one-year-old channel, OWN.

But on Sunday night, her pleas crossed a line with the Nielsen ratings company when she tweeted: “Every 1 who can please turn to OWN especially if u have a Neilsen [sic] box,” just as a new episode of her interview show, “Oprah’s Next Chapter,” began.

That tweet broke a rule that the Nielsen rarely has to enforce, reports the New York Times.

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, 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.

In Nielsen’s ratings system, an asterisk will be attached to OWN’s ratings at the time of day Oprah’s message was tweeted, noting a “possible biasing effect,” a Nielsen spokesman said.

“It is Nielsen’s policy to note attempts to single out panel members to either change their viewing habits or otherwise influence or affect their reporting,” the spokesman, Matt Anchin, said later in an e-mail.

Last November, the NBC late-night comedian Jimmy Fallon declared that he wanted to “Occupy Nielsen.” He told viewers, “This Friday, I want everyone who knows someone who’s in a Nielsen family to call ’em up” and tell them to turn on his show.

“You don’t even have to watch the show, you just have to put it on,” he said.

That Friday, Nielsen excluded Fallon’s show from its averages altogether, a much more severe punishment than the one presented to OWN on Monday.

On Sunday, Ms. Winfrey’s unusually blunt request and the misspelling of the Nielsen name caused some Twitter users to doubt that Ms. Winfrey was the one actually doing the typing. But she was, according to her executive producer, Sheri Salata, who was in the same room at the time.

They were together at a hotel in suburban Atlanta that did not carry OWN. The fact that it is difficult for some viewers to find highlights one of the channel’s problems. The two were watching the Grammys like tens of millions of others.

Five minutes after the post about Nielsen, when the Grammy Awards ran a commercial, Winfrey wrote, “Grammy people..u can turn to OWN.”

Some replied to Winfrey to thank her for the reminder, but others criticized the tone of her two please-tune-in messages. Oprah replied to one of the people who labeled her message “desperate” by saying, “‘desperate’ not ever a part of my vocab.”

Since “Oprah’s Next Chapter” began in early January, it has drawn almost 900,000 viewers on average, significantly more than most other prime-time shows on the channel. The viewership figures for Sunday’s episode, the one that will come with an asterisk, were not available at press time, reported The Times.