Connection Refused in Sap portal

Hi Everyone,

This is Raghu

I have created system object for backend CRM 7.0( Ehp2)  from Portal 7.3. It was connected successfully. when i am doing testing from  sysadmin->support->Test and configuration tool it is giving below exception

partner hostname:sapdp00  not reached

error WSAECONNREFUSED: connection refused

How do i resolve it.can anyone help me.waiting for your reply.Thanks for advance.

Thanks,

Raghu