Sender RFC Adapter

I am trying to configure my RFC Adapter and after activating I keep getting the following error:

Error can not instantiate RfcPool caused by:

com.sap.aii.af.rfc.RfcAdapterException: error initializing RfcServerPool:com.sap.aii.af.rfc.core.repository.RfcRepositoryException: can not connect to destination system due to: com.sap.mw.jco.JCO$Exception: (103) RFC_ERROR_LOGON_FAILURE: User not authorized. Session terminated

I am using XIAPPLUSER. I checked the userid password and they are correct. Also it has enough Authorization to do RFC calls.