In MS Word creating a mail merge letter using an MS Access .mdb data source,
I select Mail Merge Recipients/Edit to open and/or modify the data. This has
worked before and currently in other documents, but something has happened
and my Edit is Disabled. I used a different Edit Mail Merge Recipient
toolbar button and recieved: X This is not a valid Office Data Store.

Is this an Access problem or a Word problem?

How do I correct the problem so that my Edit button reactivates in Mail
Merge Recipient?