Field Calculation Help

Hello, on my form "INCCP Application" I have a hidden field where i am trying to auto populate it to fill in from the first name last name field.  (trying to get it to combine these field into one as i need it for a zapier integration that i am using).  however, each time, it fills the field as "0"... could you fix this for me or let me know how to?

Are you referring to hidden field "Display Name"? I have cloned your form and made some test on my cloned form, but it seems that you were able to resolve your issue. 

I have set mentioned field to be shown on my form and data that I entered inside of "Name" field are correctly passed to "Display Name" field. Also in Email Notification that I received correct values are passed. 

My cloned form: https://form.jotform.com/62036721463956 

If the issue still persist on your end, please let us know.