update form field based on dropdown value - data in second list

[LYNCHJL]

Hello, I have a form where user must select a country, then I would like to update automatically the supervisors names in a field on the same active form -- the data for supervisors is stored in a separate list which also has a country column.

Currently I have the supervisors field (people picker type) set as the following:

Filter('Portal Users', 'Supervisors' = DataCardValue2.Selected.Value) -- however  the "=" is showing as invalid.  

What is the best way to accomplish this? Many thanks!

[Pstork1]

Is the Supervisors column a People/group column in SharePoint?  If so then you are trying to compare the data card value to an object, not a string.  you need to use the property from the Supervisor's column that is equal to the selected value.