D7 Why I cannot just copy a template file from a module to my custom theme to override it? I'm using the TimeField module with a custom theme (a subtheme of the Bootstrap theme) and I want to change how the output is rendered. 

There's a timefield.tpl.php file located at 


  sites/all/modules/timefield/theme/timefield.tpl.php


which I want to modify copying it to 


  sites/all/themes/my_theme/templates/


but when I do so the copy is ignored and the original file is loaded instead. 

I'm a Drupal newbie but I like to learn, so any advice or link to a resource to understand where the problem lay is fine.
Create tpl file for field field--field-name.tpl.php. place it to your theme.


  if Field name is: field_page_photos
  then File name will: field--field-page-photos.tpl.php


copy sites/all/modules/timefield/theme/timefield.tpl.php code to above tpl file.
make changes and clear cache.