Hi,
Please refer this link (pg 10):
In your receiver SOAP - XI channel you need to give the Target URL of your ECC (R/3) system and not the destinations which u created...also u dont need any Destinations to be created in your PI NWA for SOAP - XI.
Target URL format: http://<host>:8000/sap/xi/engine?type=entry
With valid User ID / pwd needs to be configure in CC.
Hope it helps!
Regards,
Azhar