[web2py] SyntaxError: Set: no tables selected on select statement.

[Matthew Young]

Hello I am using the Version 1.99.3 (2011-11-07 17:41:19) dev version
of web2py.

I am having an issue with this view function:
def check_room_availability():
    room = db.room(request.args(0)) or redirect(URL('view_rooms'))
    reservations = db().select(db.reservation.room.name==room.name)
    return dict(room=room, reservations=reservations)

I get the following error when this page is viewed with a room number
passed as an argument:
Traceback (most recent call last):
  File "/home/mattosaurus/web2py/gluon/restricted.py", line 194, in
restricted
    in code it raises a RestrictedError containing the traceback.
layer is
  File "/home/mattosaurus/web2py/applications/roomReserve/controllers/
default.py", line 121, in <module>
  File "/home/mattosaurus/web2py/gluon/globals.py", line 149, in
<lambda>
    self.files = []            # used by web2py_ajax.html
  File "/home/mattosaurus/web2py/applications/roomReserve/controllers/
default.py", line 85, in check_room_availability
    reservations = db().select(db.reservation.room.name==room.name)
  File "/home/mattosaurus/web2py/gluon/dal.py", line 5697, in select
    db,
  File "/home/mattosaurus/web2py/gluon/dal.py", line 1225, in select
    sql_t += ' %s %s' % (icommand, str(t))
  File "/home/mattosaurus/web2py/gluon/dal.py", line 1128, in _select
    tablenames = self.tables(query)
SyntaxError: Set: no tables selected

My table definitions in db.py look like this:
db.define_table('room',
    Field('name'),
    Field('description','text'),
    Field('location','text'),
    format='%(name)s')

db.define_table('reservation',
    Field('room','references room'),
    Field('start_date','datetime'),
    Field('end_date','datetime'),
    Field('special_requirements','text'),
    Field('approved','boolean'),
    auth.signature)

db.reservation.room.requires = IS_IN_DB(db,db.room.id,'%(name)s')
db.room.name.requires = IS_NOT_EMPTY()
db.room.description.requires = IS_NOT_EMPTY()
db.room.location.requires = IS_NOT_EMPTY()
db.reservation.start_date.requires = IS_NOT_EMPTY()
db.reservation.end_date.requires = IS_NOT_EMPTY()


Has anyone seen this error before? Is my select incorrect? I am
finding the documentation a little confusing in this area.