It's been two days since I am trying to make Atmosphere work in my Digital Performer 4.12. I have been consulting with Spectrasonics support and it looks like they are not able to come up with the solution to this problem. Simply put my DP 4.12 does not recognize Atmosphere in spite all of my efforts. My setup is:
Mac G4 866Mhz, DP 4.12, OSX 10.3.7 and 2GB of RAM.
Worth mentioning is that I have installed Audio Unit Ver. 1.21, also I do include with this Spectrasonics' E-mail which I followed to the letter without much success.
Please try deleting the Digital Performer plugin prefs file.
Quit DP and then go to HD/Users/Username/Library/Preferences. Then, delete the file called Com.motu.digitalperformer.plist and delete the folder called Digital Performer tm (like the trade mark logo).
Bootup from OSX disk and use Disk Utility to repair permissions. Make sure to bootup from the OSX install CD disk 1 when using Disk Utility to repair permissions. Inside Disk Utility, select the startup disk and then click on the Repair Disk Permissions button. Run Repair Disk Permissions 3 times, one right after the other, in order to make sure everything is repaired.
Then, create a NEW session in DP and open up a Spectrasonics plugin.