[AccessD] RUN??? Save a concatenate to another field

I'm working on the Histories table now. After changing the existing Title to
Title1, and adding a new Title field, I changed the query SQL so that it is:

UPDATE Histories SET Histories.Title = [Title1] & " " & [SubTitle] & " " &
[SubTitle2];

However, when I click on Run, I get "The action or event has been blocked by
Disabled Mode". What does that mean, and how do I fix it?

Kathryn