Formula field displaying long ID instead of string value

Formula field displaying long ID instead of string value

Hello,

I have set-up 2 forms "Clients" & "Project codes". On the "Project codes" form I have the following fields:

1. Project_name << standard text field
2. Client_ID << lookup field to look up Client_ID from Clients form. Client_ID is a text string (such as "ABC" or "XYZ")
3. Project_code << formula field to concatenate Project_name + Client_ID

My problem is that when selecting Client_ID (for example: "ABC" or "XYZ"), the Project_code field reads the Project_name + a long record ID number. How can I have it show as the String value (such as "ABC") and not ID Number?

Thanks for your help!