Running python commands in a post-build event on MSBuild

I'm using the command "python setup.py py2exe" in the post build event, when I did a build on VS2008 there's no problem, but when I run my aut开发者_开发问答omate build I get the message "Project : error PRJ0019: A tool returned an error code from "Performing Post-Build Event..." and "python is not recognized as an internal or external command operable program or batch file".

The python path is already declarated at environment variables, the command runs normally if I use on the command prompt manually.

Why MSBuild can't get the right path to execute the python command?