Making Subform Field Value Available To Popup Form

In my Student Administration database I am trying to launch a popup form from a sub-form of a Job Positions and Seekers form. The sub form is actually one of 2 sub-forms, both Continuous Forms default view, on a form linked via an unbound control (MasterJobPosID).

The first sub-form is called and lists open Job Positions and the 2nd sub form is called and lists all Students Seeking each of the positions. The Students Seeking subform is linked to the unbound control MasterJobPosID in the main form which is set to equal the Job Positions subform's JobPosRecNo field which is the key to the Job Positions table.

The popup form is called Job Employment and is being launched via an event macro from the Students Seeking subform. It will allow the user to create a record in the Job Employment table. The event macro has a Where statement that says "=JobPositionID And Student", an attempt to link it to both the Job Position record being filled and the Student filling it.

I am able to populate the popup form's fields in expressions setting Default Values equal to fields on the loaded Job Positions subform and the Student from the Students Seeking subform. What I am unable to get is the Job Position record key from any of the 3 fields it appears in on the Job Positions and Seekers form:

MasterJobPosID on the main form.JobPosRecNo on the Job Positions sub form.JobPositionID on the Students Seeking subform.

I want that to link the new Job employment record to the Job Position record the student is filling. In fact I get a parameter prompt for JobPositionID when the popup form is launched.