If you read the news post on the front page, it lets you know that shares do count, but they're not displaying in the stats. You can mine with no issues, it's just a problem with the latest MPOS version that I'm fixing. It's only a display bug I'm working on fixing.

This screenshot is proof that it's just a display issue, your shares are working fine. http://snag.gy/O2FrX.jpg