I've been working through the documentation to try and set up the Indoor Space Planner solution. It's worked up to the point of creating the Space Planner app but having created the Space Planner app the next step is to create a 'Plan', but this step always fails with the following error:

I can't find any information on why it's failing. The 'Plan' creation takes very little information (basically just a title) so I can't figure out why it's failing. Presumably something is wrong with my data/map/Space Planner app but I'm at a loss to know where to look as I've followed the instructions to the letter.
Has anyone else experienced this? Does anyone know where I can look to find out what the actual problem is?
Thanks in advance.