New User question : Sourcing value from another field

New User question : Sourcing value from another field

Hi, I am new to soho CRM but familiar with other CRM's.

quick question, I want to create a field 'Initial' which will automatically source the first character from the field 'First Name', I have tried to do this with a formula field but nothing shows in the field even though the formula looks ok.

Substring(${Contacts.First Name},0,1)

Assume I am missing something very simple here? can anyone help?