In lookup field not showing

Hi -

I have a table 50001 which has Customer no(Linked to Customer Table), Tax exposure code and Expiration date. Primary key is Customer no. and Tax exposure code. Field Groups - Customer no., Tax exposure code, Expiration date. I have also created a page with all the three fields in them.

On the Customer table I have a field called Tax exposure code which is linked Table 50001 same field is added to customer card. When I click on this down arrow of the field Tax exposure code in the list it just shows Customer no. and Tax exposure code from Table 50001 but not the Expiration date.

As I have all the 3 fields in the page not sure what the Expiration date does not show.

Any help is highly appreciated.

Thanks
RJ.