In reply to ravi:
you need to disable the constraint as well using constraint_mode. I couldn’t find any specific LRM section for this rule, but following section makes this clear:
Section 18.11.1:
Normally, calling the randomize method of a class that has no random variables causes the method to behave as a checker. In other words, it assigns no random values and only returns a status: 1 if all constraints are satisfied and 0 otherwise.