Issue Running UNIX process from CRON !!

Experts,

Not sure whether the problem described here is related with Unix or is it with Oracle Installation. Here is the description of the issue:

A new Unix server is setup as a part of Unix and Oracle upgradation activity for one of the Application, I work on.
One strange thing is happening while running the processes on the new server from CRON file. The CRON is kicking the process but not able to complete it. Unlike it is giving the below message:

sqlplus: Command not found

However, running the process manually is working fine (ORACLE_HOME, ORACLE_SID and PATH is working fine). I further digged the issue and found as below:

Error 6 initializing SQL*Plus
SP2-0667: Message file sp1<lang>.msb not found
SP2-0750: You may need to set ORACLE_HOME to your Oracle software directory.

Can someone help in identifying the issue here.

searching the FAQs in these forums came up with

I suggest to source your .profile file before calling your script in cron and give it another try:

* * * * * . .profile your_script