h640p works only half of Samsung Galaxy Note screen

Hi. I plugged my Huion h640p to my Samsung Galaxy Note. It connected. I can also see the cursor moving. I can also click things. However, I can only navigate half of the screen. I cannot access the other half using the pen. When I move the cursor to the edge of the tablet, the cursor stops in the middle, as if there is a wall there. Hoping you can advise. Thanks!