How to return Prepayment amount associated with a Service order in a GI?

Hello, Hoping someone can help with this generic Inquiry (GI) question. 

I am trying to create a GI which identifies work orders having a prepayment applied.  There is a field on form FS300100 labeled “Prepayment Received”.  When looking at the Element Properties for the field, the results are:

Data Class:  FSServiceOrder

DataField:    SOPrepaymentReceive

ViewName:  CurrentServiceOrder

This field would be the perfect field to inspect to identify the Service orders in question.  However, this field is NOT populated in the generic inquiry Results Grid.  The field is blank for all returned rows.

My simple GI has only the FSServiceOrder table and I returned all fields.  I see the result row for the Service order in question, just no data for the Prepayments.  

 Any suggestions are greatly appreciated!