Ora-12154 when connecting to Oracle forms

When I started oracle Forms to create a new data blocks, I was unable to connect to the database. I got error:
Ora 12154: TNS name could not resolve the connect identifier specified

I have installed Oracle Developer suite 10g after Oracle 10g server. Platform is Windows Xp.

Solution: copy tnsnames.ora file from oracle home location to oracle developer home location.
that is,
from
d:\ora_10g\ora92\network\admin\tnsname.ora to
d:\oracle_tool\network\admin\tnsname.ora

Shutdown and restart the oc4J instance again. Try to connect again. everything work fine.

FRM-18107: Failed to create a DE context for the module

When starting Forms 10g Developer after starting OCJ4 Instance, I got the above error.
I installed Oracle developer suite 10g after Oracle 10g server. (Windows platform)
Solution is to delete Oracle Home environment Variable. I just delete Oracle Home environment variable which points to, on my system, oracle 10g server which I installed at first. And everything works fine.