That's because events bound to an element does not apply to dynamically added similar type of elements. Use jQuery's .live to bind to elements created even after you bind to events initially.
Check out this SO question, where the poster has a similar requirement to bind a plug-in to dynamically created elements -
http://stackoverflow.com/questions/5766086/using-jquery-plugins-with-live[
^] (Because applying plugins is not similar to binding to events using 'live')
Here is another answer of mine which explains jQuery's live -
Insert Input type button in HTML Table[
^]
Another option is to re-bind every time you create a new text box. Check out this link -
http://stackoverflow.com/a/1317427/312219[
^]
Hope this helps!