Error CE7375 how do I publish Attributes in OData?

Hi there i am trying to install ODATA wit the association “As an associated object id” but i have an error which i cant seem to fix. this is my error Massage:  “Attribute ID for resource “Core.Massage” must be published and should be selected as key when associations are exposed as an associated object id”   can anyone tell me how i can publish my ID attribute and resolve my error?    thank you ahead 
1 answers

Select your entity in your OData service and click on ‘Add’

You will see a pop-up where you can select the ID. Make it the key after that.