Help with formula for custom entity field. I want to reference a custom list of names. Pull the e-ma

Hello, I have created a custom form. In this form, I created a custom entity filed. It is a list of names.

Team Members

Ann

Bob

George

I created another entity field. Team Member E-mail

I have difficultly getting the formula to work.

I want to reference the "Team Members Name" - Ann. Then look at the contact record. E-mail field. Then populate the custom form with the e-mail address from the contact record.

I can not save the  Team Member E-mail custom entity field because the formula is invalid.

Can someone help me with the formula?

Thanks

Crissty