I am trying to use the jQuery input mask plug-in (jquery.maskedinput-1.3.min.js), and I have searched for several examples/solutions, and my code is exactly as other working exa
Spaces are not valid in ID attributes. You should change your id to $("#POIName") and update your html as well.
$("#POIName")
Jquery-ids-with-spaces is a similar question that you may find intersting.