Not all RLG databases have OpenURL linking. Please see the bottom of Using OpenURL in Eureka for a list.
To activate OpenURL linking, please see Activating OpenURL
The activation form asks for the OpenURL link resolver's BaseURL and the URL for the link image:
URL of Link Image
Use one of these button images or create your own.
If there are problems connecting to GODOT from an RLG database, then one thing you should check with RLG is that the underscore in 'hold_tab.cgi' is not being interpreted as an 'o' with an umlaut. This was a problem when they set up my test account. Once we realized the problem RLG was able to make the required change.