If the record source for your form is a query which uses groupings or
aggregate functions, Access defines this as a query which is *not
updateable*. You can test this out by simply running the query and trying
to update fields in the returned rows.
Make a copy of the entire application. Disable your
relationships. You will likely find you can make
changes. If you can then I suspect what is happening is
that you are violating a relationship. If you have a 1
to 1 or many relationship with enforced integrity you
have to update the primary record before you can do the
subordinate.
