illegal memory access was encountered

[longpeng2008]

when test examples: test.py
./include/cudarray/common.hpp:95 an illegal memory access was encountered, my enviroument is ubuntu 15.04 and GTM980, actually I don't know where to set CUDNN_ENABLED, so I just replace the
if os.getenv('CUDNN_ENABLED'=='1'): to if 1:,
I think it will worked, whats the issue mean?
thanks