INSTALL_FAILED_VERSION_DOWNGRADE error while trying to reinstall apk ?

Today, I wanted to install a newer version of my app over an existing install.  Even though newer apk version number is higher, it was throwing INSTALL_FAILED_VERSION_DOWNGRADE error.

After looking at the pm command line i came up with this. It worked !

pm install -r -d  test.apk

-r is to reinstall
a- allow version code downgrades