TNS-12557: TNS:protocol adapter not loadable

TNS-12557: TNS:protocol adapter not loadable

Yesterday, I have installed OBIEE11g to my laptop. Installation was successful and working fine to me. But after that I have encountered issues connecting to the database using my existing connection string. I have added these db connection string to the OBIEE11g home tnsnames.ora file but no luck.
I have did some work around, firstly checked my TNSPING, but the result showing as below

So I have checked my PATH setting and discovered the original PATH setting missing my old Oracle Home details. This below is my present PATH environment setting.

PATH=C:\Program Files\PC Connectivity Solution\;C:\WINDOWS\system32;C:\Middlewar
e\Oracle_BI2\bin;C:\Middleware\Oracle_BI2\opmn\bin;C:\Middleware\Oracle_BI2\opmn
\lib;C:\Middleware\Oracle_BI2\perl\bin

After experimentation revealed that my exiting TNS_ADMIN and bin directory has been missing from PATH environment, so I have decided to add the existing directory and now its looks like. (close the command window and open another one)

PATH=C:\OraHome_1\bin;C:\OraHome_1\network\ADMIN;C:\Program Files\PC Connectivit
y Solution\;C:\WINDOWS\system32;C:\Middleware\Oracle_BI2\bin;C:\Middleware\Oracle_BI2\opmn\bin;C:\Middleware\Oracle_BI2\opmn\lib;C:\Middleware\Oracle_BI2\perl\bin

As a result of this path setting, again open one command window (startup->cmd) and tried with same command. Now its working fine

Simple but spend some time to identify the issue.