Value List Not Displaying Values

[spectre6000]

Background:

Payment Detail Table >- Payment Table >- Payor Table -< Product Group Table -< Client Table

also: Product Group Table -< Product Table

The troublesome layout is based on the Payment Table with a creation-permitted portal to the Payment Detail Table.

Within the portal is a drop-down field for Product Number with a value list based on the associated field in the Product Table.

I've tried setting it to "show all values" and "show related values starting with..." (I've tried multiple tables). At best it will display the values from one Product Group (always the same Product Group) for a total of five Product Numbers (no scrollbar present or needed) and nothing more.

How do I get the value list to display the Product Numbers associated with the Payment's respective Payor's Product Groups?