There are a couple of causes for the ProjectionCalibObj.cpp, Line 801 error:
1. There was a problem in early versions of Didger 3 when converting the projection of images calibrated in the polyconic projection - the result was solid black and the error you report was generated. Didger 3.07 fixed this problem.
You can check which version of Didger you are using by going to Help | About Didger. If you are using a version of Didger earlier than 3.07, you can update to the most recent version by going to Help | Check for Update.
2. This error was also generated when converting the projection from Stereographic to Mercator. Fundamentally, this is just not going to work because the poles cannot be shown in the Mercator projection. They are at an infinite distance from other parallels on the projection. The lower latitudinal limits in the Mercator projection are about 80 degrees S. Mercator projection is just not designed for polar regions.
Updated July 18, 2018