dataTables editor error 'Column Not Found'

Hi, I am trying to join two tables and I've followed all the examples as closely as possible
but I keep getting this error when I run the file ('suspension_editor.php' in a browser); I am expecting to get a set of well formed JSON objects.

{"error":"SQLSTATE[42S22]: Column not found: 1054 Unknown column 'report_eligibility.emp_status' in 'field list'","data":[]}

That column does exist in my database. I've updated the config.php file to make sure I am pointing to the right db with the correct credentials. My only guess is that the leftJoin is not working.

Help is much appreciated! Thanks, Tom

Editor::inst( $db, suspension')
    ->fields(
        Field::inst( 'report_eligibility.emp_status' )->validator( function ( $editor, $action, $data ) {
        if ( $action !== Editor::ACTION_READ && $_SESSION['read_only'] ) {
            return 'Cannot modify data';
        }
    } ),
        Field::inst( 'suspension.emp_id' )->validator( function ( $editor, $action, $data ) {
        if ( $action !== Editor::ACTION_READ && $_SESSION['read_only'] ) {
            return 'Cannot modify data';
        }
    } ),
        Field::inst( suspension.nuid' )->validator( function ( $editor, $action, $data ) {
        if ( $action !== Editor::ACTION_READ && $_SESSION['read_only'] ) {
            return 'Cannot modify data';
        }
    } ),


        Field::inst( 'report_eligibility.last_name' ),
        Field::inst( 'report_eligibility.first_name' ),
        Field::inst( 'report_eligibility.region' ),
        Field::inst( 'suspension.school_name' ),
        Field::inst( 'suspension.course_name' ),

        Field::inst('suspension.begin_date') ->validator( 'Validate::dateFormat', array(
                "format"  => Format::DATE_ISO_8601,
                "message" => "Please enter a date in the format yyyy-mm-dd"
            )),
        Field::inst( suspension.end_date' )->validator( 'Validate::dateFormat', array(
                "format"  => Format::DATE_ISO_8601,
                "message" => "Please enter a date in the format yyyy-mm-dd"
            )),
        Field::inst( 'suspension.notification_date' )->validator( 'Validate::dateFormat', array(
                "format"  => Format::DATE_ISO_8601,
                "message" => "Please enter a date in the format yyyy-mm-dd"
            )),
        Field::inst( 'suspension.attempts' ),
        Field::inst( 'suspension.comments' )

            )
            ->leftJoin( 'report_eligibility',   'report_eligibility.nuid',   '=', 'suspension.nuid' )


    ->process( $_POST )
    ->json();