PIA Adapter : unable to get a connection from the pool

Hello,
I was trying to connect to PeopleSoft through WebMethods. I have the PIA adapter installed. I am using oracle database. I created a new Alias name and I have created a new connection pool setting , but when i am tesing the alias , I get the following error:

Testing failed. Error:- unable to get a connection from the pool.

In the log the error is :

ERROR - method - 1: DOWNbea.jolt.ServiceException: Invalid Session; Explanation: ;
ERROR - unable to get a connection from the pool.ConnectionPool.ConnectionEntry.ctor fails; unable to open connection

Please let me know where exactly I am making the mistake.

Thanks in advance.