Looks like it's taking very long time to retrieve the list of tables from SAP system. There's a lot of tables and if you are on a slow connection it can take a while (especially if you haven't used it in a while, succeeding retrievals usually go much faster because of caching). So let it be like that for a while and eventually tables will probably be fetched. Then you can review the reason for the slow retrieval (look on network speed between client and SAP system and also the performance & load of the SAP system you are connecting to).
It says CommunicationException, which indicates there's problems establishing the network connection to the SAP system. It could be firewalls, slow connection, etc. You can find more information about the exception in the log files generated.