Recipient e-mail in send mail fails

I have a send mail action us to send mail to a database query

I can get the mail to send to a recipient if i statically type in the e-mail address but whenI connect the e-mail address using the data link it fails. I can put the same data in the “To Name” field and it populates the data fine?

Why does the same data that appears in the To Name fail when I put it in the ToEmail field