Incompatibility between UMAT and varied versions of Abaqus

Hi everyone,



     I encountered a problem while runing a UMAT in Abaqus 6.9, which
kept aborting with a systme error code 693. The UMAT is wriiten in
Abaqus 6.5 and prove runing well in 6.5. But when putting it in 6.9, it
always failed. I can not figure out what going on there. Do you have
good ideas?



     The error message is like

 

    The system erro code 693



    CONTACT FORCE ERROR TOLERANCE FOR CONVERT SDI=YES                
1.00   



    Thanks!