I have been trying to set up automatic backups for Retrospect Server, which is installed on Mac OS X Lion. It has worked on several new iMacs, also running Lion. When I try to back up an older iMac (Intel) which is also running Lion, trying to add the client directly returns accurate information (name, address, client version,) but returns this error: "an error occurred (-506)." I have been unable to add this client. Any ideas?