The IDoc Trace functionality only works for IDocs exchanged between partners of Partner Type LS (Logical System).

In order to be able to make this synchronous RFC, the partner profile of the LS, which represents Integration Server, must contain an outbound parameter with message type SYNCH.

Also the Function Call to an LS of type "tRFC Port", like Integration Server, is only executed if the SAP system is of release 4.6D or higher. For older releases you have to apply the following hot packages: