This in an indication that the BES Client can’t post results to its parent. There could be lots of reasons for this, please check the following:
Hit that url from the computer, see if it resolves correctly.
Make sure port 52311 isn’t blocked.
Ensure ‘bigfix’ resolves to the BES Server from the computer.
Check to see if the FillDB folder on the BES Server is full. Clients can’t post if the FillDB folder is backed up. If the client can register with the parent but not post results the FillDB folders are usually full.