Object OutboundDeliveryRequest does not let you edit the value of custom fields

Hello everyone,

I am currently working with the SAP Cloud Applications Studio system where I have a problem, what I have done has been to extend the standard object OutboundDeliveryRequest and I have added some custom fields.

Later in the BeforeSave code of the Root node I tried to give a value to the fields, but it did not work.
Is there any restriction with this object?

Thank you!