I am unable to connect Forms 6.0 with Oracle 8.1.7 (On windows 2000) from Client machine. Listner is started on Server. In sqlnet following error observed :

Tns error struct:
nr err code: 12206
TNS-12206: TNS:received a TNS error during navigation
ns main err code: 12545
TNS-12545: Connect failed because target host or object does not exist
ns secondary err code: 12560
nt main err code: 515
TNS-00515: Connect failed because target host or object does not exist
nt secondary err code: 1004
nt OS err code: 0