Primary_Contact=crmResp.get("First Name"+"Last Name"); Not Working

Primary_Contact=crmResp.get("First Name"+"Last Name"); Not Working

Apologies for the seemingly simple question but I am very new to the whole Zoho world.

I have built an app in Creator that has a Zoho CRM field that pulls from Contacts to populate fields on my form.
One of the fields is called Primary Contact which I would like to put the Full Name (First Name + Last Name)

I CAN get Primary_Contact to equal First Name OR Last Name but not both, I don't know if I can concatenate First Name and Last Name but everything I have tried doesn't work :-(

My code below works for Last Name but when I try to change it to 
Primary_Contact=crmResp.get("First Name"+"Last Name");  it doesn't work.   



-------my working code----------
crmResp = zoho.crm.getRecordById("Contacts",input.Primary_Contact1_ID);
// a MAP is a paired array of keys and values; 
// use variable_name.get("Key") to return it's value
Primary_Contact=crmResp.get("Last Name");
Email=crmResp.get("Email");
Phone=crmResp.get("Phone");



Really appreciate your assistance and I look forward to learning and contributing in the future.

Sean