CF-18 Digitizer Pen handling

I've bought an cf-18 on ebay, but did not know, that this is an digitizer, not a touchscreen-version.
The digitizer-pen is a small pen like u possible know from the PDA, but with a small electronic-circuit in it and a button on the side ( and i saw it also with a button on the back for the erase-function).
My problem is, that i must press the pen really hard on the screen to make a click.
Is this normal or should the pointer on the pen make a noisy click? Someone tried to open the pen? Or should i change the values of the small trimmer under the second button (maybe it will change the frequence or the sensibility)?

Thanks forward. And again sorry for my poor english.