I created a new window so I now get the tab but it is empty even though I have defined some.
Robohelp 8 is installed on my machine so I have that dll file.
By having RoboHelp on your PC you would certainly think the HHActiveX.dll would be present and registered. What is your operating system? Windows XP? Vista? Windows 7? And what version? 32 Bit/64 Bit?
Have you tried following the steps to register the DLL with Windows?
Additionally, you should consider reporting this to Adobe as a bug. I have a link in my signature are that points to the page you use.
Helpful and Handy Links
I have Windows 7, 32 bit. Yes, I have tried registering the dll.