I am using a Panasonic Lumix. The Eye-Fi card had been working beautifully. We've had it for about a month. However, about a week ago I began getting an error, "insert valid SD card". I pop out the card, put it back in, most of the time it takes several tries to get it to work. I've missed a few good pictures, and have started carrying around a regular SD card as back up. Any ideas?