Why would this query return this error?

Hi, all... Why would this query return this error: 'Unknown column 'properties.mls_number' in 'on clause' Here's the query: <cfquery name="get_properties" datasource="#application.dsn#" cachedWithin="#CreateTimeSpan(0,0,0,0)#">             select     p.property_id, p.mls_number, p.street_number, p.street_name,                 p.city, p.state, p.remarks, p.property_type, p.list_price,                 o.mls, o.office_name, o.display_order,                 min( pp.photo_filename) as prop_photo_filename        from     properties p, offices o, property_photos pp   left join     property_photos          on     substring_index(properties.mls_number, '_', 1) = property_photos.photo_mls_number         and     p.mls = pp.mls   left join     offices          on     p.listing_office_mls_id = o.mls_office_id         and     p.mls = o.mls                  where     p.property_type <> 'rental'                     group by     properties.mls_number    order by     offices.display_order       limit     10        </cfquery> Suggestions? Thanks! Rick