|Why would you want to spend money on (or even use) a separate keyboard and touchpad for a laptop which already has both?? |
Anyway, try disabling the laptop's touchpad as it may be conflicting with the external one. You can disable the laptop's touchpad in Device Manager. Right-click the Touchpad item and choose "Disable". Then restart Windows.
When you decide you want to use the laptop's own touchpad again, go back into Device Manager, right-click the touchpad item and choose "Enable". Restart Windows.