Hi Ish,
please compare with ecc hier with bw hier, you may find out where its causing.
As said by above, at ECC side, please recheck your hierarchy nodes, if any nodes are not in place. take functional guy help and do the requried changes.
after that activate ecc hierarchy and replciate into bw side. do the activation further steps.
Please check this link.
http://scn.sap.com/message/5566706
please check this note:
Note 1308643 - Consistency check: Nodes that are not included in hierarchy
Thanks