I think i misunderstood validation rules, so i answered the following challenge creating a validation rule that only applies if the insertion is different for what i write in the rule:
AND(ISBLANK( Account.Id ), OR( MailingPostalCode = Account.ShippingPostalCode ))
I mean, if the insertion/update is correct, then do it, else display error message.
The challenge has succeeded.
My question is, am i wrong or i should write in the validation rule the conditions where should'nt be accepted?
Here is the challenge