Traffic quality is a common issue with Crakrevenue, they're pretty strict about it. What I've seen is that using expired domains can be a bit of a grey area, as the traffic isn't always targeted. It's likely that the conversions aren't meeting Crakrevenue's requirements, which is why they're not paying out. I've had similar issues in the past and it usually comes down to the quality of the traffic, so it's worth looking into that. The support team is on the right track by pointing that out, now it's just a matter of refining the traffic sources to meet their standards. It's also worth noting that Crakrevenue has specific geo and device requirements, so it's possible that the conversions aren't meeting those either.