Omap3530 IDLE Entry

Hello Everyone,

        Here I have a problem. I find it difficult to configure Omap
into Idle Mode.
I refer to this article:

I followed every step, and every step works fine. But after I excuted
WFI, CORE Domain didn't entried RETENTION. Did I miss something? Or
is there anything left to be done?

Any Suggestion would be appreciated!

Best Regards