Trigger is not subscribing documents

Hi All,

I am publishing a document from A server and subscribing on B server. Document is not getting subscribed on B server but when i locally publish on B server i am able to subscriber on B server perfectly. But from other server like A to B is not working.
I found below error in my server logs. please let me know what is the issue.

2018-08-24 14:23:47 EDT [ISS.0153.0042E] webMethods Messaging Trigger PackageName:triggers:subscribeBusinessPartner failed: com.wm.lang.flow.FlowException: [ISC.0064.9314] Authorization Required: Unauthorized