Hello all. I am trying to simulate the pulling of a liner through a pipeline using Abaqus CAE. The system consists of an outer pipeline, liner and rope (to pull the liner), and I am trying to model the tension present in the rope as it is pulled. I have defined the parts, materials, sections, profiles and steps, and applied a displacement. However, to correctly simulate the system, I need the liner to 'drag' along the bottom of the pipeline due to gravity. This requires the addition of tube-tube interactions (ITT21 elements) in the input file. However, when I try to run the simulation, I get an error stating that I have not assigned sections to elements in the Liner, when I believe that I have. Can anyone advise why this is the case? I have attached a copy of the input file and warning message I receive. Thank you for your help in advance.