Have (and love) HP Pro Tablet 608 G1. Both on the internet a proper active pen specically designed for this tablet. The pen is per the HP table that shows proper tablets for specific devices. The pen is N9D47AA, P/N 823178-001. As per the instruction, the pen selects the item (the small little circle on the touch screeen can be seen), but upon lifting the pen, it does not open the item. Nor can I use it to write anything ... What do I do wrong?