Cause - Dead batteries and/or incorrect installation
The batteries shipped with the keyboard/mouse may be dead.
1.Be sure to try brand new batteries.
2. Also ensure the receiver is not blocked or otherwise out of range of the keyboard/mouse.
3. When attempting to sync or re-sync the keyboard and mouse, press the connect button on the receiver until it begins to blink. Then press the connect button on the keyboard or mouse until the receiver light stops blinking; this step must be completed for both the keyboard and the mouse in order for both to be properly recognized.
4. If there are multiple wireless keyboard/mouse setups in the same area, be sure to follow the previous step one unit at a time.
5.Once each keyboard and mouse has been connected to its respective PC, they should not interfere with each other.
6. Interference should not occur so long as the keyboard and mouse are both connected prior to moving on to the next machine.
7. If interference does occur (ie: moving the mouse on one machine affects another), then re-sync the offending keyboard and mouse set until they no longer interfere with another machine. This may take a few tries and may require re-syncing of all keyboards and mice, but the end result should be free of interference.