Need help for running UMAT of Dr. Huang's single crystal

Hello Everyone,

I am a new member of imechanica. I have started to learn UMAT of Abaqus to model my material behavior ( Cu6Sn5, HCP) using crystal plasticity finite element model. I found Dr. Huang's single crystal UMAT to start learning UMAT and I thought that it would be a great guide to start though it is written for FCC mat. But unfortunately I was not able to run the UMAT with it's input file.

It is showing error " Too many attempts were made for this increment". I have no idea where I went wrong as I just ran the UMAT with it's own physical model. Please can anyone provide me a running UMAT of Dr. Huang ? I think there is something I need to change. Also, guideline for learning UMAT will be a great help.

I have used the following code and devided into .inp file and .for file.

http://www.columbia.edu/~jk2079/fem/umatcryspl_mod.inp

Also , I am using Abaqus 6-12-1. Please help me on this issue. 

Please mail me at soudchoudhury@gmail.com

Thank you so much.