not familiar with LUSAS either, but ...
is it complaining about element #1 (a "2D QTF8" element) ?
this is part of the base of your channel ?
if these elements are supposed to be in global planes, what doe it do with the narrow band of elements that are forming the corner of your channel (at 45deg to global planes) ?
why would it want elements to be in a specific plane ??
possibly it's had a nervous breakdown and the message is not really the problem ??
another day in paradise, or is paradise one day closer ?