The most common problem that arises when casting is a bad internet connection. Your device may have a weak internet connection, or the devices aren't all connected to the same Wi-Fi network. Go to the network settings on your device and your smartphone or tablet. Ensure both connect to the most robust Wi-Fi possible and that they're on the same band (2.4Ghz or 5Ghz). Another issue with your video not casting correctly is that you may have the wrong input selected on your television. Using your TV remote, toggle between HDMI selections or verify which one the Chromecast uses by checking the connections on the back. If Prime Video is casting, you should see a message on your computer or smartphone screen that looks like this: If you're using a smartphone, you may need to check your low-power mode settings. The low-power mode can prevent casting because it's trying to preserve battery life. Toggle the option off and retry casting.