First if the machine is getting an IP address from a DHCP server check that you are getting the address that you expect. If it is a manual configuration check the IP address, subnet mask and default gateway. The machines need to be on the same network to speak to each other.
If there is a router or firewall in between the systems you are trying to connect to make sure the appropriate rules are in place to allow the traffic to pass through. Come back and give more information and I will clarify my answer.