Are the tables in the same directory as the database? How did you create the different versions of the database and tables?

Each table contains a pointer back to the database, and the database contains a points to the tables. It's possible to mess these up by moving things around in an unexpected way.

Try the following:
close all
set defa to ..wherever your DBC is located
use xxx.dbc [whatever the dbc s called]
browse for objectype='Table'

This opens the database container as a table. Look at the 7th column [U_case], it contains the pointers to the tables. These may be absolute paths, or relative to the location of the DBC. If they are absolute paths, and you move the DBC and tables to a different directory you will have problems.