First verify that the agent is up and running on the workstation(s) and you can ping the Endpoint Server from the workstation(s) by name and by IP.If the agent was pushed out using the SMC then the DLP Agent Package may not be configured correctly.
Navigate to DLP IC<Agent Deployment<vX... Agent Deployment<DLP Agent Package.
Check the Programs tab for the command line script and see if the command line script has "Hostname" for Endpointserver instead of the actual name or IP.
By default this will just be 'hostname' which will not tell the agent what ENDPOINTSERVER it needs to communicate with.
Uninstall the agents you deployed using the SMC console and redeploy with the corrected DLP Agent Package.
If you only have a few agents that need to be fixed you can also manually correct the situation by logging into sqlite3 at the endpoint and entering the following command;
UPDATE configuration set value=’xx.xx.xxx.xx’ WHERE setting=’AggregatorHost’;
enter in your IP address for the 'endpointserver'
Restart the agent service after doing this. When you check Agent Management Overview the Agent will appear on the list.
Make sure your DLP Agent Package still gets corrected for future deployments.