Although NATURAL is an interpreted language, it still generate some kind of object-like-module that is created when you CATALOG, STOW or CATALL.
Within this module, NATURAL keep track of files and their origin. If a view was specified, and that view came from a DDM that contains an FNR and DBID, then NATURAL imbed their values into this "module".
Then, when executing the module, NATURAL is looking for these specific FNR and DBID (in your case: 233/6).
There are several solution for this issue.
First direction is to use DBID=0 in the DDM.
The other direction is to use logical files table, and point the DBID/FNR to other numbers at run time (there are at least 3 ways to achieve this).