question about orientation for polycrystal plasticity

Hi everyone, 

I am trying to build polycrystal plasticity model based the UMAT of Prof. Huang .In order to assign different initial orientations to different grains, I defined sections of material in my input file and grouped all the elements which constitute a grain in one section.In each section'material ,I changed  the first vectorand and the second vector, which represent grain's orientation.  Now,My inp file can be submitted,but the .exe was aborted with this information"Error in job multigrain: The executable C:\SIMULIA\Abaqus\6.11-1\exec\standard.exe aborted with system error code 145."

The problem how to define initial orientations to different grains has confused me for a long time.Someone said I can  specify the orientation through the props array,but I do not know how to modify the Rotation Matrix in UMAT.

can someone tell me a detailed way to define orientations to different grains?
Thanks

Erik