Symmetry region, Linear Periodic, “linear shift”

[Halipio]

I am trying to apply at a model on ANSYS workbench 15.0 a symmetry region, linear periodic according is described on the page 37 of this manual:Link , however I do not know what the parameter “linear shift” stand for. When I define this parameter, the following error appears on the meshing generation : The mesher cannot find matching topology for the following topology. Please verify that the topology is the same shape and size. Also verify the position and orientation of any associated coordinate systems.

Someone know, how to define this parameter correctly.