C2H timming issue

I am using c2h to accelerate my algorithm now

I can successfully generate hardware accelerator

But when I download the program in Nios IDE(8.0)

It's not successful:

Using cable "USB-Blaster [USB-0]", device 1, instance 0x00

Pausing target processor: not responding.

Resetting and trying again: FAILED

Leaving target processor paused

here is total logic elements: 22,113/33,216 (67%)

When the the system only take <30% total logic elements include accelerator, it's can successfully download program to hardware with IDE

And my program memory is sdram

I am suspect may be there is some problem about timming in sopc?

is any body have the same experience or any suggestion?