ODBC Connectivity

Hi,

While getting ODBC connectivity to oracle backend I am getting problem “TNS cannot be resolved”
I check server connectivity also that is fine. I am using WIN98 as OS and Oracle 7.0 as backend server.
I am using server name ORCL, username and password as SCOTT and TIGER.
If anybody has face same kind of problem please write me the solution.

Bye
Zabin