Have you tried relocating the remote sensor for the temperature sensor? The dashes being displayed is saying that the clock is not getting the signal from the sensor to determine the temperature reading. Try placing the sensor very near the clock to see that it will receive the signal.
Make sure you have good batteries in your wireless sensor. Press and hold snooze button for five seconds to synchronize the clock and the sensor. Red led on sensor will blink while communicating with the clock. Dashes on the clock will blink until it picks up the temp from sensor.