“cannot find DHCP server”

In MMC on DHCP server 1, I cannot expand DHCP server 2 (It has a red circle with a white X.) However, on DHCP server 2, MMC looks fine with both DHCP servers listed; I can expand them both. Do I have a corrupt DHCP database on DHCP server 1 ? If so, what do I do to fix it ?
Environment is Windows Server 2003/Active Directory.