As a footnote to this issue, we have been having the same issue when starting wM from a service (no issue when starting from server.bat. We had librfc32.dll in the %SystemRoot%\System32, but it seems wM could not find it, we have found this issue recently with other adapters and this is how we resolved it and reported it back to wM on the SR opened for the SAP adapter:
"It seems that when running webMethods as an NT service, sometimes it does not pick up the path correctly. When this happens, you need to specifically put the path in the server.bat. For example, in this case the SAP adapter needs to find LIBRFC32.dll in the %SystemRoot%\System32 directory. Even though webMethods reports that %SystemRoot%\System32 directory is in the path, it seems not to find it when the server is starting the SAP adapter. To correct this problem I changed the following in the server.bat:
set PATH=%PATH%;%IS_DIR%\support\win32;%IS_DIR%\jvm\bin\classic;%IS_DIR%\lib;
to read :
set PATH=%PATH%;%IS_DIR%\support\win32;%IS_DIR%\jvm\bin\classic;%IS_DIR%\lib;c:\winnt\system32;
Then restarted the server and now we are starting webMethods as an NT service and it works great… no SAP adapter problems."