You are probably limited to two simultaneous Bluetooth connections at once. The Keyboard and Mouse count as two separate devices and the remote is already connected, so when the 3rd device attempts to connect, it will boot off either the device that is connected the longest or another device with the same profile ( I don't remember which).

You can probably get around this by using a USB dongle type wireless device through a USB OTG hub or using a Bluetooth Keyboard that has a built in trackpad.

I was able to fix it by when the box thinks the mouse is connecting to the box but when you just hit the back button on the remote the connection stays and now started to work with the remote the keyboard the mouse and my Xbox game controller all at once.