Auto complete not working in another code block under the same session

I tried the code as shown in the example document. I first import matplotlib.pyplot and numpy in the first session code block In the org-mode ipython mode buffer for this code block, I can get auto complete after I do np. or plt. However when I started another code block under the same session, the auto complete no longer works. It was clearly shown working in the screenshot provided by @gregsexton, so I wonder if anyone has the same problem and could give me some suggestions? Thanks in advance

Some information:
I use Elpy for the python mode, which use company mode for auto completion.