Part of the problem, industry experts say, is that lenders are having trouble keeping up with demand for short sales and foreclosures. “There is a lot going on all at one time,” said E. Robert Levy, the executive director of the New Jersey Mortgage Bankers Association. “It’s a very, very difficult problem no matter how you deal with it.” Nationwide, the number of short sales increased by 22.4 percent to 30,766 in the third quarter of 2009, according to the Office of the Comptroller of the Currency and the Office of Thrift Supervision. About one in 10 residential sales last year was a short sale, according to the National Association of Realtors. Joe Zinman, chief executive of Aurora Financial Group in Marlton, said he used to deal with just one short sale at a time. Now, he might be handling as many as 15 at any given time.