• by Mark Walsh  @markfwal, July 25, 2012

Social gaming service Zynga on Wednesday reported lower than expected financial results for the second quarter, “citing short-term challenges” that led to lower bookings. The company posted a loss of 3 cents per share (or profit of 1 cents a share on an adjusted basis) on revenue of $332.5 million.

Wall Street analysts had forecast earnings of 5 cents on revenue of $344 million.

Among the company’s key metrics, average daily bookings per user fell 10% in the quarter from $0.051 a year ago to $0.046. That means Zynga isn’t making as much off each user as a year earlier.

Among other measures, the company said daily active users increased 23% to 59 million, while monthly active users went up 27% to 151 million from a year ago. With the company’s focus shifting increasingly to mobile devices, Zynga noted its mobile user base has grown five-fold in the year to 33 million daily active users, or more than half of the total.

Partly because its $200 million acquisition of Draw Something has proven a bust, the company is lowering its full-year outlook. It also cited delays in launching new games and a faster decline in Web games because of a “more challenging environment on the Facebook platform” for the diminished forecast.

It expects bookings in the range of $1.15 to $1.22 billion for 2012 and earnings per share of 4 cents to 9 cents. Analysts had projects full-year earnings of 27 cents a share.

Zynga's stock price fell sharply in after-hours trading following its earnings announcement. The company's results don't bode well for Facebook, which reports earnings on Thursday. It's stock was also down in after-hours trading.