ANSYS WB/CFX FSI problem

I am trying to model a tube closed at the two ends by 2 plates.  The cavity enclosed by the two plates and the tube is filled with fluid.  I fix one end and apply a force to the other end.  The tube is a very flixible material and thus all the force should be present as a pressure detected by the fluid.

 When I try to do 2-way-FSI in ANSYS WB with CFX, all the force is taken up by the tube and none by the fluid.  any suggestions?