errors with pex

Hey guys i was just wondering if someone could help me with my server, after doing permissions the server began to getting 'internal server error' when someone tried to join, please help me out thanks

Error messages o startup:

Code:

18.07 03:57:01 [Server] SEVERE at ru.tehkode.permissions.PermissionEntity.initialize(PermissionEntity.java:57)
18.07 03:57:01 [Server] SEVERE at ru.tehkode.permissions.PermissionEntity.getOptionBoolean(PermissionEntity.java:298)
18.07 03:57:01 [Server] SEVERE at ru.tehkode.permissions.PermissionUser.getOption(PermissionUser.java:132)
18.07 03:57:01 [Server] SEVERE at ru.tehkode.permissions.PermissionUser.getGroups(PermissionUser.java:221)
18.07 03:57:01 [Server] SEVERE at ru.tehkode.permissions.PermissionManager.getDefaultGroup(PermissionManager.java:277)
18.07 03:57:01 [Server] SEVERE at ru.tehkode.permissions.PermissionManager.getDefaultGroup(PermissionManager.java:288)
18.07 03:57:01 [Server] SEVERE at ru.tehkode.permissions.backends.FileBackend.getDefaultGroup(FileBackend.java:145)
18.07 03:57:01 [Server] SEVERE java.lang.RuntimeException: No groups defined. Check your permissions file.

 

need to post your permissions.yml go to www.pastebin.com paste and link it

 

Last line of the error should give you an hint on where to look for the fault.

"18.07 03:57:01 [Server] SEVERE java.lang.RuntimeException: No groups defined. Check your permissions file."