I reinstalled the XLN installer, went to the advanced tab from the installer and located where my 64bit version of Addictive Drums 2 was installed. I went to options in ST 1 / Locations / Vst. Ensured that the path from the XLN installer window matches the path where the .dll file is located in studio one. On the same window (in Studio 1) check the rescan at startup check box and click on the reset blacklist option. Click Apply and ok. Close and reopen St1, IT WORKED!!!!!! I have been trying this for a while and I finally got it to work. I hope this helps.