This usually happens when you don't enter your serial number exactly. The most common mistake is mixing up the letter L and the number 1. The next is the letter O and number Zero (0). Notice the letter is more round than the number (move oval). The best way to ensure you have the serial number correct is to log into your Roku user account and copy the serial number from your devices list and paste it into the web page.
Remember the HDMI extender is only for Roku Stick players, which as the players that plug directly into the HDMI port without using a cable. If you enter a serial number for any other Roku device, it will reject as well.
This usually happens when you don't enter your serial number exactly. The most common mistake is mixing up the letter L and the number 1. The next is the letter O and number Zero (0). Notice the letter is more round than the number (move oval). The best way to ensure you have the serial number correct is to log into your Roku user account and copy the serial number from your devices list and paste it into the web page.
Remember the HDMI extender is only for Roku Stick players, which as the players that plug directly into the HDMI port without using a cable. If you enter a serial number for any other Roku device, it will reject as well.
There's nothing special about the Roku HDMI extension, it's just a short (4 inches or so) HDMI cord with an HDMI plug at one end and an HDMI socket at the other. I use a non-Roku one several feet long to locate my Streaming Stick in an equipment closet on the other side of the wall from my TV.
You may be able to find an HDMI extension locally and not have to wait for someone to ship it to you. Alternately, you can use a standard male-to-male HDMI cord and connect it to the Streaming Stick with a female-female HDMI connecter.