The blue tooth Anker key board used to work with my tablet but started behaving weirdly after I upgraded to Android 4.4.2. It connects and appears to work but once I type "n" it will begin to repeat the letter endlessly aftwards. I would think it was a mechanical problem but it works fine with my phone running Android 5.1. I have seen comments on the web that suggest it is incompatible with android 4.4.2. I tried the External Key helper demo app that people have suggested but that did not help and I have not seen any other suggestions of a work around or a fix. I would upgrade if I could but despite rumours there is a lot of doubt that Samsung will upgrade this tablet ( not impressed with that either). Can anybody help?
I don't know if this will help at all, but I had a problem with the Shift Key not working when I had a USB keyboard plugged into my Android phone and I found a solution. Maybe the solution I found for my problem will fix your problem as well. If not, I do apologize.
I have a Samsung Galaxy S5 Android phone. I purchased a USB external physical keyboard that can connect with my Windows computers and my Android devices (via micro USB). The keyboard worked fine when I plugged it into my Windows computers. The keyboard worked pretty well Android phone, except for the fact that the Shift Key didn't do anything when I held it down and pressed other keys (to capitalize letters, type symbols found above the number keys, etc.). I tried a lot of stuff to get the Shift Key to work on my USB keyboard when I had it plugged into my phone. I couldn't get the Shift Key to work when I used the stock Google/Android keyboard app, the Samsung Keyboard app, or the SwiftKey Keyboard app. After a lot of trial and error with apps and settings (and a lot of frustration), I FINALLY came across an app that DOES solve the Shift key problem: The "Go Keyboard" app on the Google Play app store.
After I installed this app and set it as the default keyboard app on my Android phone (Samsung Galaxy S5), the Shift key worked just fine when I used it while it was plugged into my Android phone (allowing me to capitalize letters and type symbols above the number keys).
I hope this works for you, too!