When connecting Facebook Groups to dlvr.it, Facebook now requires the additional step of adding the dlvr.it application to your Group's allowed applications list before posting will be allowed.
These steps can be performed either before or after connecting the Group to dlvr.it, but this procedure needs to be performed for each Group connected to dlvr.it for posting:
1) Log into your Facebook account
2) Navigate to your group
3) Click on More, then click on Edit Group Settings
4) Scroll down to Apps, then click on Add Apps
5) Click on dlvr.it from the list
-- NOTE: Facebook sorts the list case-sensitively, so Facebook displays dlvr.it at the end of this list - along with other apps whose names begin with a lower case letter.
6) Click on the Add button on the screen that pops up
7) You're all done!