You should check if the device allows multiple WiFi connections. The device can often be the main cause of why it's not working. I'm sure you can check the settings, there you should be able to configure this problem. If not, I recommend you to read about it on
WiFi Trends
. I always find my solutions there. They have a great website, with a vast area of subjects related to technology. But my strongest advice would be to use one network at a time. It's easier this way and saves you a lot of trouble.