Shell Programming and Scripting

I have created a script to strat and shutdown Oracle 10g DB on Solaris automatically when UNIX reboot. In the begining, it worked well. All of sudden, the dbstart part didn't work, other 3 part for lsnrctl, emctl, isqlplusctl all worked fine. I think it was TNS_ADMIN variable got problem. Because dbstart need to go to /var/opt/oracle/ to find oratab file. In that file there is a line: my_oracle_sid:$ORACLE_HOME:Y. This will indicate that DB should start up when UNIX reboot. Then dbstart utility will work.

I am not sure that my observation is right or not. Please help me to solve this problem. If my guess is right, can I set up TNS_ADMIN variable (TNS_ADMIN=/var/opt/oracle export TNS_ADMIN) in .profile or I have to set it up in my script. Following is the sample of script for your reference.

#!/bin/sh
ORACLE_HOME=/u01/app/oracle/product/10.2.0/db_1
ORACLE_OWNER=oracle
if [ ! -f $ORACLE_HOME/bin/dbstart ]
then
echo "Oracle startup: cannot start"
exit
fi
case "$1" in
'start') # Start the Oracle database and listener
su - $ORACLE_OWNER -c "$ORACLE_HOME/bin/dbstart"
su - $ORACLE_OWNER -c "$ORACLE_HOME/bin/lsnrctl start"
su - $ORACLE_OWNER -c "$ORACLE_HOME/bin/emctl start dbconsole"
su - $ORACLE_OWNER -c "$ORACLE_HOME/bin/isqlplusctl start"
;;

I set up TNS_ADMIN in my .profile as above and rebooted the server. All other 3 agents started automatically. I did $ORACLE_HOME/bin/dbstart, the server responded as 'VER10LIST=10: is not an identifier'. So where is the problem? I have another UNIX server running the same script, it worked perfectly. No idea. Please advise.