Hi,
kindly check the below steps.
1 ) Path sap/xi/engine not active
2 ) Activate the service engine in transaction SICF
as described
pls go through the below troubleshoot ing guide link.
https://websmp203.sap-ag.de/~sapidb/011000358700005909032005E/PI70-701_Trouble.pdf
Regards
Srinivas