I couldn't define sweep outputs because of improper workbench window configurations
workbench icon doesn't display in the ribbon under analysis tab for S4L 5.2.1.1375
Are you perhaps using Sim4Life using Remote Desktop or TeamViewer, or something similar? There are sometimes issues with the graphics drivers when using those software, preventing the Workbench to work correctly. If that's the case, there should be some warnings/errors in the Console when you start Sim4Life, mentioning issues with OpenGL.