what does dpkg -s amsn tell?

Also take a look to the option --force-remove-reinstreq... I think that this will fix the issue, but after that I suggest you to re-install and then re-remove the package.
If --force-remove-reinstreq doesn't work, try --force-all.

I DON'T KNOW IF THE ABOVE ACTION WILL DAMAGE YOUR SYSTEM. DO THEM AT YOUR OWN RISK