Hello Jonas,
Could you please check if your TMS configuration is consistent (A message is displayed on the STMS screen in case of inconsistency in the TMS configuration for the Domain system).
In case of Domain Links, it has been experienced that the RFC(s) are not generated / the TMS configuration is inconsistent due to mismatch in the password of TMSADM user for both the connected domains.
Thus you may user report TMS_UPDATE_PWD_OF_TMSADM to have a common password for TMSADM across all connected domains & properly generated RFCs for all systems across-domain.
Please refer the below link for details.
http://scn.sap.com/message/14648807#14648807
Please let me know in case you have any doubts.
Best Regards,
Tanmeya