Why can't you use Visa, MasterCard or American Express at vending machines? You can, but it costs more than it's worth, so far.

USA Technologies Inc., Malvern, has been trying to change that, and losing money, for ten years, say analysts Thomas McCrohan and Leonard DeProspo at Janney Capital Markets.

The product, the ePort card reader, "makes sense," but "profits have been hard to come by," McCrohan writes today in a report to clients.

As vending machine prices rise above $1, people are more reluctant to use them. U.S. vending sales fell 5% last year, to $22 billion, the analysts wrote, citing data from Automatic Merchandiser. One problem: People carry less cash as they switch to cards.

Revised: Machine suppliers and operators would love to see more card-readers. First Data, MasterCard, Visa, Aramark, Coca-Cola and Pepsi have all agreed to use USAT machines. The company has raised $48 million from stock sales since 2005, and "remains virtually debt free." It's already the sixth-largest manufacturer of U.S. point-of-sale terminals (although that's not as great as it sounds: The top three, VeriFone, Ingenico, and Hypercom, control over 95% of the U.S. market, and 70% worldwide).

Yet USAT shares are in the basement, despite the company's projections it'll be profitable by late next year. Impatient rebel shareholders are trying to unseat founder George R. Jensen's allies on his board, as my colleague Mike Armstrong wrote recently.

What's the problem? Vending machine operators make just pennies on the dollar, and "weren't willing to purchase these devices for $500 per device or more," DeProspo told me. Newer, smaller version are available at $329, or a limited-service model for $199, plus $10 a month, plus 5% per purchase.

Makes sense, McCrohan says, for public laundries and other relatively large coin-machine purchases. But so far there are only around 65,000 card-readers (most of them by USAT) at 8 million U.S. vending machines. Instead of ramping up, USAT has been cutting staff: "They recently laid off 20% of their employees, and are now operating with 43," says DeProspo.

Without taking sides, Janney says it's only "NEUTRAL on the shares because we believe it will be difficult for the company to accelerate the pace of growth to the rate necessary to create positive oeprating income," McCrohan concludes.