Under the vast majority of circumstances, ZEMAX will run without any troubleshooting required at all. In rare circumstances, however, you may find that ZEMAX issues an error message or requests that you enter a license code when you attempt to run the software. 

This article assumes that you have already installed the Sentinel key driver and the latest ZEMAX Update from the downloads page. If you have not installed these files, please do so before continuing. The Knowledge Base article "How to install ZEMAX for the first time" can assist you in this process.