I have seen this error if the permissions on the endpoints are not correct. Have you pushed the ACLs to these machines? I would also check the contents of the users and users.local files on the machines causing problems.
What is in the rscd.log of the targets?
Can also occur if the target is running an old agent version, you might want to check that.
Yes YOu are correct, there was issue on permission.
Now I have corrected export and user.local file, it should work.