Error when generating statistics on single field

I'm trying to create a report that counts the number of times a term in a CCK field is found within all records of a content type. I get the following error:

user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ' nid, node_data_field_os_field_os_value, node_type, node_vid ORDER BY node_dat' at line 7 query: SELECT node.nid AS nid, node_data_field_os.field_os_value AS node_data_field_os_field_os_value, node.type AS node_type, node.vid AS node_vid FROM node node LEFT JOIN content_type_serviceform node_data_field_os ON node.vid = node_data_field_os.vid GROUP BY , nid, node_data_field_os_field_os_value, node_type, node_vid ORDER BY node_data_field_os_field_os_value ASC in /home/sysadmin/public_html/techstaff/sites/all/modules/views/includes/view.inc on line 769.

I've tried multiple combination of settings. If I group on NID the errors go away and a report is generated with each record showing (1) next to it.

Thanks!