error while using altera monitor program to connect to altera de2 70 kit

i have created a nios ii system using sopc builder. and i tried to use altera monitor program to run a program in de2 70.

but i get an error saying

"Using cable "USB-Blaster [USB-0]", device 1, instance 0x00Resetting and pausing target processor: FAILED

Leaving target processor paused"

can any1 please help me why this error appears?