Hi,
Take basis team help and ask them to see the WE05/20.
partner profile need to be active.
Ask basis team to maintain proper logical mappings between ECC and BW.
table - RSLOGSYSMAP(table need to have ECC and BW server technical names as source and target respectively)
Seems like basis team may wrongly maintain destination.
please check table - RSLOGSYSDEST - need to have correct target details.
Ask basis team to reset the whol RFC ports between ecc and bw.
T code - SM59.
Thanks