The online unit at AOL Time Warner(NYSE: AOL) is slumping again, and the company blames advertising softness. Although management maintained its company-wide guidance for revenue and that silly little EBITDA thing (earnings before interest, taxes, depreciation, and amortization), it said the America Online unit would not meet targets.

If you're interested in the numbers, full-year advertising and commerce revenues will come in around $1.7 billion, but there's even a 5% downside risk to that. Good thing the rest of the company is doing better; overall, look for full-year revenue growth in the 5% to 8% range.

So is the online ad market still declining? The answer is probably "no." AOL's press release blames the shortfall on "continued softness in America Online's advertising business," not the ad market in general. A quick spot check of our sources confirms there really hasn't been an industry-wide decline in the past few months.

Instead, America Online's troubles seem to be specific to its own business and may be the result of the timing of contracts and renewals. If that's true, and if advertisers are renewing at lower rates, we can expect the current revenue projections to be more the norm, rather than just a dip.