Oracle Database Discussions

Hello
i have a problem to connect my database
error ora-12545 Connect failed because target host or object does not exist
I checked on the forums for similar error
tried all recommandation like
check hosts file, ping server ... but nothing

My connection is like this
i have one oracle db server on a RHEL 5.4
i have one oracle client on another RHEL 5.4

i tried to connect to the db via the client but it does not work
i have configured my connect string (orcl)
tnsping work : tnsping orcl
Still i cannot connect to db server

here is another thing
when i type sqlplus the prompt comes for
username
after password
and then i got error ora-12545 Connect failed because target host or object does not exist

but

when i connect like this : user/pass@orcl
it brings me back to shell prompt without giving error**
like it logs in and logs out just after

Is there any log i should activate or check ?

What should be done to correct this ?

Any idea would be appreciate ?

Thanks