sg-dma from altera wiki example design on nios

Hello

I used the sg dma example design from

http://www.alterawiki.com/wiki/file:sg-dma.zip

I run that on arriaV

the qsys connection are as the following

ram -> tx sgdma -> fifo st -> rx sgdma -> ram

the design is waiting for and "blocked here"

while(tx_done == 0) {}

Can you help how to debug ?

Thanks!