[. . . ] Getting started with Logitech® Wireless Touch Keyboard K400 1 K400 Getting started with Logitech® Wireless Touch Keyboard K400 2 1 2 3 4 5 English Features Hotkeys 1. [. . . ] € If the Unifying receiver is plugged into a USB hub, try plugging it directly into a USB port on your computer. Check the orientation of the batteries inside the keyboard, or replace the two AA alkaline batteries. € Remove metallic objects between the keyboard and its Unifying receiver. € Try moving the Unifying receiver to a USB port closer to the keyboard. € Try reconnecting the keyboard and Unifying receiver using the Logitech Unifying software (Refer to the Unifying section in this guide. Did you know you can add a compatible Logitech wireless device that uses the same receiver as your current Logitech Unifying product?If you have a Logitech wireless device that’s Unifying-ready, you can pair it with additional Unifying devices. Just look for the orange Unifying logo on the new device or its packaging. [. . . ] Logitech assumes no responsibility for any errors that may appear in this manual. [. . . ]