Infopackage file preview problem

Hello Experts,

I've created an infosource using another infosource as template and deleted one characteristic from the new one. I've activated the transfer rules and created the infopackage.

I deleted the corresponding column from the flat file used for the template infosource, saved it under a new name and specified this in the external data tab.

When I try to preview this file, I get a conversion exit error for fisc period. So I selected this exit and executed it with a single fiscal period data value. Output came without any issue.

What is wrong with my infosource/infopackage?

The comm structure and transfer structure don't list the characteristics in the same sequence as the flat file but since the template infosource does not either, I didn't worry about it.

I would appreciate any help.