This is probably due to a known bug in the Canopy Package manager which blocks some package updates after a Canopy application update (most commonly after updating to Canopy 1.2).
This bug has been fixed in Canopy 1.3, due out at the end of January 2014.
Meanwhile there are several workarounds:
1) The easiest and cleanest solution is usually to follow the instructions in the section "Starting over with a clean set of Python packages" in the article "Updating the Canopy application and its Python packages".
Note that this will delete any 3rd party packages which you installed (e.g. with pip or easy_install). If this would be too painful, there are alternatives:
2) You can update the package using the "enpkg" command line utility.
3) Caution, fragile: You can remove the package in Package Manager, then close and restart the Package Manager. You will now see the package as being installed but not removable. (Reason: Canopy User Python is now inheriting this package from the Canopy Core installation, which is not changeable by Package Manager.)
This should work fine short-term. Long-term, it may cause you problems, because any time that the package is updated within a new Canopy application update, the new version will immediately be visible in your User Python Environment, which has the potential to break your user code. (Normally, updating the Canopy application does not touch your User Python Environment, so that packages are only updated when you say they should be.) So 1) or 2) are more robust solutions.