There is no way of scoring "No Dp" in this test. Even if you answer once or twice to only one of them the tests says you have mild depersonalization. Everybody in their lives feel spacey or their mind is somewhere else from time to time. I don't think the test is accurate as the cambridge scale. You DON'T have it as a disorder even if you experience some of those from time to time. It might be as simple as an anxiety symptoms which is the case for the most of the people. This topic is extremely misleading.
Yeah, Steinberg's DP questionnaire, similar to her book, is designed to encourage people to take the SCI-D, which - surprise, surprise - requires an expensive session with a trained interviewer. As far as I'm concerned, it's a con and this questionnaire has no place being passed off as a valid instrument for assessing DP.
The CDS (the original Trait version) is a validated diagnostic tool. The CDS-State is a crude measure of severity and is useful for measuring progress during treatment.
Since this thread is pinned and we already have a pinned thread dedicated to validated instruments, I'm removing the tests from the OP. The list of symptom domains is what's useful here. As for tests, all 3 major instruments (CDS-Trait, CDS-State and DES) can be found here.