Hey, I have the same problem.
Basically, I have a fresh unmodified tekkit server up and running successfully.
I download and install permissionsbukkit, terminal says permissionsbukkit loaded correctly, etc.
Use terminal command to set myself to group "admin," without even opening the config.yml file
Log in to the server, I don't have a single permission. /help, /sethome, nothing works.
However, I can still build and chat.
Am I missing something here?
I've tried searching for any special relation between Tekkit and PermissionsBukkit, and even config.yml files that are designed to work with tekkit, but the information is just not there.
EDIT: I think another thing worth mentioning is that when I use /perm check <node> <player> every single node defaults to false. Not sure how this is even possible since the permissionsbukkit defaults allow even non-grouped users to use /motd and /help
EDIT2: I just removed permissions... but I still get "You don't have permission" when I type /help, /motd, etc. so I just feel confused and violated. I'm gonna go cry myself to sleep now.