Dear , 

R u using Smartobject using Smartbox services , or Smartobject using Other services ?

Best regards.

Hi Ahmad,

Thanks for your quick reply. Its smartbox services.

I managed to add the field now, i had to check in the form, then go back in and this time when i clicked top left, the add a field button appeared.

Kind Regards

Dear , 

Ur welcome , 

I didnt exactly understand if u found the solution or not , but in case u didnt , after u add a data field to the smartbox 

Then it will upgrade auto , and u will find it in the list view ,

u have to go to ur list view , Checkout ---> Edit 

and u can find the new field on the right pane that looks like this ,

Here u can drag the field u want and drop it inside ur list view .

Best regards .