I'm getting the following error when I click "Try It" for problems from the library:
No display module found for path '/admin/Undefined_Set/1/'. at /usr/local/webwork/webwork2/lib/WeBWorK.pm line 158.
It looks like you are using the library browser in the admin course. The admin course is only intended for doing site administration tasks, like creating courses. Try "try it" from a regular course.
John
That did it -- thanks!