When I search for a client using "Search Client" it doesn't pull the client name

I have only made one appointment using a clients name.
Obviously I can see the appointment in the "Active Appointments" area because it is the only one.
BUT, I wanted to test the "Search Client" function.
I put the clients name in the "Search Client" field and click "Search Client", the system says "No appointments have been found".
Why would this be?