From your snapshot, it shows the latest Output Set ID is 42. Is that the Output Set you specified for Post Processing?
Also, if you had previously run a Linear Statics analysis and specified a stress Output Vector for display, and the new Output Set is from a Normal Modes or Heat Transfer analysis, you will not have that stress Output Vector available for display, so you'll need to respecify a new Output Vector.
The fastest way to activate an Output Set is via the Model Info pane, where you expand the Output Set object tree, right-click on the Output Set you selected, then select Activate from the menu.
The file cannot open, probably due to the embedded spaces in the file name. Please remove the embedded spaces in the file name and repost it.
The file is too large for our forum. Please delete all the output sets, run the File > Rebuild command on the model, save it with a different name, then zip it up without any blanks in the zip file name and post it.
In the mean time, perform the following two (2) checks:
1) Verify that your Analysis Sets have Boundary Conditions assigned as well as Output Requests as shown below:
2) In the PostProcessing toolbox, click the Select Output Vector icon, and that should list all of the Output Vectors available for the Output Set as shown below: