Sm59 error in ecc -connecting to po

Hello Experts,

I am trying to connect my Ecc system with my newly installed Sap PO.

I have created RFC destination in Ecc sm59 but it throws the error as :

Error Details      ERROR: Transaction program not registered

I have created Destination in PO and I was able to ping Ecc successfully.

I have configured the properties of Inbound RA in PO as recommended with just one exception that

As per the SAP recommendation the value of  Parameter MaxReaderThreadCount should be 5 to 10 .However, when we change it to any other value then 0.it fails and gives error.

So can this be the reason that RFc destination fails.If yes how can we resolve this.

Thanks

Naveen Tripathi