Cannot generate printed documentation

Last week I started a trial of Robohelp 2015. I am using it on Windows 7 with Word 2013. Last week I generated printed documentation for a project that I created many years ago with Robohelp 9 and Word 2010. It worked fine without any problems. Today, after making some changes to the documentation I tried generating the printed documentation again and nothing happened. The SSL came up as usual and I clicked "Save And Generate" and then the warning about overwriting the docx file came up and I clicked OK and nothing happened. The Output View window stayed completely blank and no docx file was written. Can you help me please?