Isnt there an option in the DBPro IDE to manage your plugins ? I dont use DBP but I would think that there would be an option to "Activate" your registered plugins somewhere( I understand that you need to enter an "Activation Key" and have it confirmed online before the plugin will become active and usable).. If you are entering your key, make sure that you are entering it exactly as its shown, matching the case(i dont know if its case sensitive, but better safe than sorry), if that still doesnt work and you have a valid purchased key, I would suggest contacting the TGC support guys as the problem may be external to you(ya might have been given the wrong key or something.. check ur using the activate key and not the serial number or something, you know, ive made that mistake myself before with other productcs lol)
I also remember reading in the installation emails I recieved when I purchased DarkPhysics something about activating the plugin and how, after its installed for DBP, I didnt pay much attention though as I'm a GDK user and dont have to worry about activating plugins lol... but perhaps you missed something in one of those emails ? .. also check all of the documentation that came with it, both in the install dir and your email confirmations/reciepts( the ones that contain the activation key for the plugin )
Good Luck..
If it ain't broke.... DONT FIX IT !!!