Ansys problem with highly distorted elements

[ngoctt]

I am trying to run for some models with hyperelastic material (Ogden's model) and large displacement static in Ansys. I took the material parameters from literature which are well-known for rubber. But I always had a problem as follows: 'One or more elements become highly distorted...' and the program stopped. The models were very simple (just tension and compression tests) with good mesh shape and the load was not to big (deformation was not too large, just 1%). I am using Ansys 12.0 Academic research license. I only could run these models when I decrease the load to a very small one. Please see attached the ansys files and error.
Have you ever seen this problem before? Do you have any idea about that problem? I would highly appreciate if you could give me any suggestion/solution.
Thanks and best regards

Tran