Hi Martin Carmody,
there could be several reasons for this. I am seeing that you are using a very old Visualize version (2016?). In that case, one likely reason could be that the SW assembly is of a newer file version (SW 2017, 2018, or 2019) that Visualize 2016 cannot handle.
You could also check the log file which should be here:
Reminds me of many conversations I've had with the Wife....
Wife: Damn ! Every time I try do do this I get an Error Message....
Me: (Trying to help) Okay Honey, What did the Error Message say ?
Wife: I don't know. Whenever I get the Error Message I just close the window....