Intially, I thought Whatsapp has a counter on their end. But I have 3 devices. Iphone and N9 failed. But android never fails in verifying. How can the results differ when it is stored on their end? Besides it might be too much of a coincidence that they clear my counter right after i cleared. Plus, i think the Whatsapp team is based in Mountain View and I cleared my device at 11am GMT+8. Anyway, like I say, I am just sharing what worked for me.