I can’t add server 2003 to domain, help!

I updated my Windows NT 4.0 primary domain controller to Windows server 2003 sp1.
Then I loaded Windows server 2003 sp1 on another server (new), when I try to add this computer to the domain, I get this error:
a domain controller for the domain mycompany.local could not be contacted

details:
The following error occurred when DNS was queried for the service location (SRV) resource record used to locate a domain controller for domain mycompany.local:
The error was: “This operation returned because the timeout period expired.”
(error code 0x000005B4 ERROR_TIMEOUT)
The query was for the SRV record for _ldap._tcp.dc._msdcs. mycompany.local
The DNS servers used by this computer for name resolution are not responding.