Default Bargaining Unit on Create a Job Requisition Page based on FTE on Position

Summary:

We are trying to default Bargaining Unit field on Create a Job Requisition page based on the value of the Union field on the Position. When we used a warning message to check if the page is fetching the value of the Union on the Position by selecting the given field value in VBS, it is returning undefined.

Expression below

[[ 'Display ' + $fields.RecruitingJobRequisition.position.UnionId.$numberValue() ]]

We are using Position to Create a Job Requisition.