>For some reason I cannot create a relation between two tables in my database by dragging the field name to the related table field name. Table are invoice and customer tables, with cust_num being a common field and the key field in customer table.
>
>Any idea why this would all of a sudden be a problem (not just these 2, but won't work with any tables in any databases I have set up, even though it did before) and any work arounds or ideas for fixing? Many thanks in advance.

Hmmmm... are you sure that you have primary keys set up for the tables? Open the database exclusively and do a "clean up database" from the "database" menu.'

Also, you need to drag and drop onto the index not the field.