We added another service name in our database server. And I added a new TNS entry to tnsnames.ora and was ready to go... I was expecting too much :( I kept getting ORA-12154: TNS:could not resolve service name.
TNS was working fine.. I could connect to it using SQLPlus and toad. It struct me only when I tried to run my application. After wasting enough time on it, I decided to give up and do a google. And it was solved by changing the access rights of the orahome directory - which is drow me insane.. I didn't do any thing with that. I just edited the damned tnsnames.ora...
Update: Forgot to mention, I synchronized both the tnsnames.ora files in ora9 home and ora10 home