HELP!!! Qsys PCIE miss interrupt signal

I run the "PCI_Express_in_Qsys_Example_Designs" sample on "Cyclone IV GX starter kit" board.

Running SGDMA successed.

i want to know wheather dma is ended by using interrupt. but i can't get the interrupt notification all the times.

Environment is:

WindowsXP SP3

Jungo WinDriver

PCIE send "legacy level-sensitive interrupt"

Steps:

1. enable interrupt at 0x0050 register

2. clear interrupt state 0x0040

3. useing WDC_IntEnable register IntHandler function

4. listen in IntHandler function

5. clear 0x0040 interrupt state in intHandler function

6. printf("Got a interrupt\n") in IntHandler function

I can't get the interrupt all the times.

I also got the same result by using "MAILBOX" testing.