C.2.80 There are no structures to choose from in the structure...

This error occurs when;

Using the File>Parameter Files menu, check which Parameter files are loaded. Ensure the scale of the loaded files match that of the layout. Alternately a new Structure could be created using the Group command.

Refer to section 2.5.5 for detail regarding Parameter Files or section 2.9.3 for detail regarding the Group command.