Processor not responding

I established a basic NiosII system in SOPC Builder,just like this:Cpu-NIosII/s,Jtag Uart，on chip memory-16K,led_pio-8 outputs.

I run the hello_led poject on my SOPC board-ep2c20,

after download my hardware system to the board and complie my software in NIOS IDE ,I run the project,but it couldn`t success.

The error informations are:

Using cable "Nios II Evaluation Board [USB-0]", device 1, instance 0x00

Pausing target processor: not responding.

Resetting and trying again: FAILED

Leaving target processor paused

I have cheched my Pins assignment , it was all right.

Please ,Please tell me how to solve?