In your context you use the wrong constant. You must use the constant STYLESHEETPATH for the path to the active child theme. The constant TEMPLATEPATHget the path to the parent theme, that was referenced in the child theme.
But, a important hint. The constant is deprecated, see the ticket #18298 for more information. That’s is the point that you should use the function get_stylesheet_directory() to get the right path.
Additional also the hint, also the constant TEMPLATEPATH is deprecated and also here the hint to use the associated function get_template_directory().