Rep. Yvette Clarke (D-N.Y.) may have suddenly and inexplicably become one of the richest Members of Congress last year.

But probably not. More likely it is simply one of the myriad mistakes — or mysteries — on the annual financial disclosure forms filed by Members of Congress.

In previous years, Clarke has listed essentially no assets or outside income.

But in May, she filed a financial disclosure form listing two Oppenheimer mutual funds, each valued at $5 million to $25 million, neither of which generated any income. There is no indication how the assets were acquired or why they weren’t on her previous forms.

If it were true, it would make Clarke one of the two dozen or so richest Members of the House.

But the entries are probably simply mistakes, Clarke spokeswoman Ronnie Sykes said. “She doesn’t own assets of that size,— Sykes said.

Clarke was unable to review the reports Monday in response to Roll Call’s inquiry, so Sykes said they were not sure exactly what the entries were supposed to indicate. But the Congresswoman will fix the forms as soon as possible, she said.

Rep. Grace Napolitano (D-Calif.) also submitted a disclosure form with mysterious entries.

In February, Bloomberg reported that Napolitano made a personal loan to her campaign in 1998, charging 18 percent interest, and has made thousands of dollars in income off the transaction. On the disclosure forms she filed in May, Napolitano reported the loan as an asset worth $50,000 to $100,000, which produced $50,000 to $100,000 worth of income. But she also listed it as a liability worth between $50,000 and $100,000.

Napolitano’s form also indicates that last June she purchased something called “4-Plex— for between $250,000 and $500,000, which generated $15,000 to $50,000 in rental income last year. But there is no further indication of what 4-Plex is. Napolitano’s office declined to comment for this story.

Rep. Henry Brown (R-S.C.) filed a disclosure form that raises an interesting question: How can you sell a property in a transaction valued at between $100,000 and $250,000 without earning any income off the sale? Particularly when the same property — a rental property north of Charleston, S.C. — was valued at between $50,000 and $100,000 on previous forms?

The answer, is you can’t.

Brown told Roll Call that he actually did make money from that sale — he doesn’t recall exactly how much — but the profits were offset by losses he took in the stock market. “We sold a bunch of stock and had some losses, and the losses offset the profits,— Brown said.

While that is a valid tax strategy, House rules appear to require each transaction to be accounted separately for the purposes of disclosure.

Rep. Emanuel Cleaver (D-Mo.) appears to have run up against a different technicality.

Cleaver reported on his May disclosure form that he earned $24,924 as a minister at St. James-Paseo United Methodist Church in Kansas City and another $1,000 in speaking fees from the Cascade United Methodist Church in 2008.

But the House Ethics Manual states that for 2008, the limit on outside earned income for Members of Congress and senior Congressional staff was $25,830, meaning Cleaver exceeded the limit by $94.

Cleaver’s office did not respond to Roll Call’s request for a comment for this story.

The House Committee on Standards of Official Conduct reviews Members’ financial disclosure forms each year, but apparently it did not catch these errors.