Niek L.
Before we address your current problem, let me describe a bit about what is currently happening. First, when working with TestStand, the .tws file that is created when you save a workspace file is something that can only be opened in the Sequence Editor environment. Which explains why, when you try to open this file using the Simple UI you get an error. Since you can't open a workspace file in a Simple UI the search directory that your workspace uses is not valid.
The easiest way to address this situation is to create a custom search directory from TestStand»Sequence Editor»Configure»Search Directories... then select Add. This will allow us to hard code a path that will reference the appropriate directory that the workspace is located in. We can then move this custom search directory to the top of the list. Now, when we use the use the Simple UI we will be able to load that sequence file because it is now part of the available search directories. This should also allow you to be able to load your custom report generation.
A_Ryan
AES
National Instruments