如何让PyCharm检查PEP8代码风格？

I'm using PyCharm (v 2.7.2) to develop a Django app, but I can't get it to check PEP8 style violations. I have enabled "PEP8 coding style violation" in the "Inspctions" section of the settings, but PyCharm doesn't highlight the style violations. Is there a way to fix this?I'm using PyCharm (v 2.7.2) to develop a Django