sys\alt_dev.h: No such file or directory

i am using Altera monitor program to compile and load into cyclone ii DE2 board.

and i am also using audio core

it's header file contains another header "sys\alt_dev.h" which is located in nios2eds directory. even though i included the path of this header it could not find the file it gives the error as

"sys\alt_dev.h: No such file or directory"

please i need help in this