Is this a new domain? Yes?
- Then, first, it can take anything from 24 - 72 hours for DNS/nameserver records to fully propagate. Second, different networks will update at different times during this period. That is, bear in mind that just because one provider has updated their records, it doesn't mean that another will.
- Changing the name servers only directs the domain to the new hosting provider. You'll need to add the domain to your account there or forward the domain to the new domain if you want everything to appear at the new domain.
- Every single hosting provider handles this differently, so you may need to get in touch with them for more details.