oithim_yew This usually happens when the server in question has been added but for some reason the collection has stopped.
If you go to the server list on the left hand pane and choose the server in question are you seeing a collection issue message? If so click on the Diagnose Issue link to get more information.
Sometimes you need to reenter the password for the server and ensure that your ports to that server are open. If all that is ok and you still having this issue, I suggest opening a support ticket or if you are in a trail contacting your sales contact so they can get you in touch with our pre sales engineering team.
You can check the settings (for port and password) by clicking on the Pencil and Gear Icon at the top.
I hope this helps!