restarting McASP+EDMA3+Int without system reset on L138

Hi,

I am having a problem in running the mcaspPlayBk example, that every time I re-load the program via JTAG, the audio is lost. The only way is to get the audio back is to do a system reset. Without the system reset, the EDMA3 ISR seems never called. I figured the problem could be 

1. McASP not generating EDMA3 event
2. EDMA3 event does not trigger CPU interrupt.