I agree. A little bit more information is required, like OS or Panda3D buildbot Version you are using.
You can also assert a few things up in front:
1.) Bullet is quite new and not available in very old Panda3D versions already flagged as “1.8”. So make sure to have a brand-new buildbot version installed. Best would be not older than two weeks.
2.) Can you see the libpandabullet.dll in Panda3D’s /bin folder? (assuming your OS is Windows… similar for other OS-es)
3.) Do other Panda3D imports work fine in the very same script, e. g. “from panda3d.core import Point3”?