You are using NPrinting 17.3 or a prior version. You have imported a table in levels.
You get one of the following error messages when you run the report or you click on preview:
"An error occurred in elaborating the entity tags. Please check if the entities are properly placed inside their level tags."
"The preview request failed because node [...] received an ApplyFailureResponse from request [...]"
"NPrinting 17.5: The preview request failed with message: Specified cast is not valid
You may also get wrong data instead of an error message, for example the same entry for all the level values.
The issue is due to these bugs: OP-2415, OP-2918, OP-3093, OP-3096
The problem is due to different bugs that are solved in NPrinting 17.3.1. The only solution is an upgrade to this version or to a higher release.