Hi,
The certificates should be installed under TrustedCA's in NWA (Netweaver Administrator). Aside from that, you should be posting to either:
https://host:port/XISOAPAdapter/MessageServlet?channel=p:s:c where p=party, s=service and c=channel
or
https://host:port/XISOAPAdapter/MessageServlet?senderParty=FP&sen
derService=FS&interface=IF&receiverParty=TP&receiverService=TS&in
terfaceNamespace=IFNamespace
Hope this helps,
Mark