Capstone Turbine Corporation (CPST) reported fiscal third-quarter earnings after the market closed today and didn't do a lot to impress investors. Revenue was up 11% from a year ago to $37.0 million, falling well short of the $40.3 million Wall Street expected. Gross margin did increase to 20% from 14% a year ago, but the company still lost $2.2 million, or $0.01 per share.

Backlog increased to $160.4 million from $149.8 million in the fiscal second quarter, showing continued demand for micro-turbines. The hope for management is that the demand will allow the company to reach breakeven EBITDA, which would be an important milestone because it would end a long-running cash burn.

The challenge is that investors are expecting a lot of profit growth in the future, given the company's $508 million market cap. That's a lot to live up to, and slower-than-expected top-line growth is a concern.

With just $132.1 million in revenue in the past year, the stock is worth nearly four times sales, a hefty premium for a company that's not profitable and isn't growing terribly quickly. Shares are sliding after hours, and I'd expect that to continue unless Capstone can pick up growth and profits in coming quarters.