A couple of things to try:

First, try setting the time that the data is valid larger than the update frequency. That way if for some reason it can't update exactly on time it will continue to show the last data until it can update. I have the update frequency set to 30 minutes on mine, but if for some reason it can't get new data the old data is good for up to 2 hours.

Second, make sure the system clock is set correctly. When the weather is downloaded it also gets the current time from the server. Say for example the time downloaded is 2:00pm and you have it set up so the data is valid for 30 min, but your system clock says it's 3:00pm, then it will think the data is expired almost as soon as it's downloaded. Somehow the time on mine got messed up and it took me forever to figure out that this was the reason my weather always showed N/A.