Calcuation based on portal value

[GameTapper]

I am trying to write a calculation for a field that will compare a fixed date to a list of dates within a portal. If any of the portal lines has the fixed date then the script should return a value of "Yes." Within the portal the fixed date will never occur more than once per record.

This is what I've come up with, but it is only returning yes if there is only one entry in the portal and the entry matches the fixed date:

If( MultiplayerInServiceDate = Dates_Titles::AirDate;"Yes";"")

where MultiplayerInServiceDate is fixed and Dates_Titles::AirDate is the field within the portal.

The actual portal is in a layout that is based on the Titles table, not the Dates table.

I'm using FMP 8.03 on WinXP.

Thanks!

G$