Check whether your listener is running by using lsnrctl status command and When using JDBC connection, are you setting ORACLE_HOME, LD_LIBRARY_PATH correctly.
Which version of JDBC thin driver you are using ?
Also check your CLASSPATH
If you are using JDK version 1.2 or above
ORACLE_HOME=YourHome
LD_LIBRARY_PATH=$ORACLE_HOME/lib
CLASSPATH=$ORACLE_HOME/jdbc/lib/classes12.zip
export ORACLE_HOME LD_LIBRARY_PATH CLASSPATH

If you are using JDK version 1.1 or so then CLASSPATH should be
CLASSPATH=$ORACLE_HOME/jdbc/lib/classes111.zip



Sanjay

[Edited by sanjay92 on 05-16-2002 at 04:13 PM]