Android, track Memory by DDMS, "Get Allocations" doesn't do anything

As the title of the question said. Steps I did:

1. click on Update heap
2. In Allocation Tracker tab, click "Start Tracking"
3. Click "Get Allocations"

In the console, I saw red messages saying:

[2013-12-29 13:56:40 - ddm-heap] *** Received REAL`

What happened? am I missing anything?

Thanks