Concatenate Function Not working?

[Lisaexperientia]

Help!  I am trying to create a field that combines first and last name.  I am using the formula below but getting the error message as shown.  Confused what I am doing wrong?

[Sho]

Hi @Lisaexperientia,

This article would be helpful.
Using Formulas in Airtable's Primary Field | Airtable Support

Strings can be concatenated in the following ways

"a" & "b" & "c"

CONCATENATE("a", "b", "c")