Issue with Crystal Reports

OK.. I was asked if I could include the planner on the Job Traveller.
Realizing that the Jobhead table was part of the report, I figured adding in
the PersonID would be no problem. This field does exist in the table. Yet
in Crystal, why can I not insert the field.. it is not on the list of fields
under the Jobhead table. Is my thinking off or does Crystal not work the
way I was told in that as long as the table is there in the report, you can
grab that field.. please advise.