Query won't work off of identical databases

[Drew]

I have a query that is based on two other queries (they
feed a larger query that a report uses). They are all
select queries, no make-table, etc.

The query runs fine against the production oracle
database. However when the query is run off of either of
the two identical test databases (production was dumped
into test within the last week), the query stops with an
error of Invalid Operation.

The Help Screen (see below) doesn't seem to apply to
anything this query is doing. Any thoughts?

Invalid operation. (Error 3219)
Possible causes:

You tried to write to a read-only property. See the Help
topic for the property to determine whether it is
read/write.
You tried to use a method or property on a type of
Recordset object that the method or property does not
apply to. See the Recordset object summary topic to
determine which methods and properties apply to a given
type of Recordset object.
You tried to append a property to a Properties collection
of an object that does not support user-defined
properties.
You tried to use the Update method on a read-only
Recordset object.