错误消息“没有配置iPhone OS设备已连接。”是什么意思？

Yesterday I testet a lot on my device. Suddenly I get this error message when I hit Build & Go in Xcode. First, it asks me if it's ok to sign with my key. I click yes, and then that error message appears. My iPod is connected as usual, iTunes starts automatically and I close that to prevent interruptions.Yesterday I testet a lot on my device. Suddenly