Custom Function - using Lookup across two apps

Custom Function - using Lookup across two apps

Hi all,

Looking for some help. We have two apps (Planner and Works)

In works I have a form that uses a lookup to get a list of places from Planner.

I've created a custom function in planner that will pull the address.

But when I am trying to get the address to populate when the right address is selected from the lookup it keeps saying expecting string but encountering BIGINT.

I've searched for an answer for a couple of hours and can't find anything that helps.

Please let me know if you know how to fix!

Thanks!