Ensure that the time period indicated on the time slider is in the recent past or very near future. That is, unlike METAR/TAF and Winds Aloft displays, Radar and Satellite are not predictive so we can't show data for the future. However, as a convenience, we do 'ghost' the last radar and satellite image for a few hours after it was processed. Be sure to look at the message area above the Chart for the time that each was processed. Also note that we process NexRad radar data every 15 minutes based on government data that is no more than 15 minutes old. However, satellite data is at least two hours old due to government processing.
Also, Seattle Avionics processes data from NOAA servers. From time to time, the NOAA servers go down. During that time, we cannot process satellite or radar data.