Bárbara:
I think your problem looks like this:
You have two databases with the same name in two different directories.

In your project You are using the path stored in the project´file.

When you loads agin fox, it loads the path saved as default in options menu.

Then you try to open the table, the table exist, but the database it have is not the correct one.
If it is not the case, take a look to the header of the table.There you can find wath exactly database you are using with this table.

And, chech in your dataenvironment the properties of the cursor.

I hope it help.

Miguel.