Abaqus UEL subroutine

Hi,

I'm working on the article " A finite element implementation of a coupled diffusion-deformation theory for elastomeric gels". It is a very nice tutorial for implementing fluid diffusion and large deformations of elastomeric gels as a user-defined element (UEL) subroutine in the commercial finite element software package ABAQUS. The subroutine and input files of the solved examples in the paper are published online. The problem is, when I want to run the input files, I got the error "Analysis is being terminated from a user subroutine".

The subroutine and input files are available here:

http://ars.els-cdn.com/content/image/1-s2.0-S0020768314003278-mmc1.zip

Would you possibly help me?

Thanks