If you machine have multiple instance then, you need to specify the instance name.
Other wise use only IP/ Name.
Please check on which port SQL server is running
Run this Query through sysadmin
e.name as ProtocolName
,ec.local_tcp_port as Port
,ec.local_net_address as IP
ec.endpoint_id = e.endpoint_id
e.name = 'TSQL Default TCP'
Then use IP,Port and try again.