Hi, as some seem to have problems with this, here is a quick explanation.

The goal of js_include mechanism is to add calls of the js files into the HEAD portion of the generated HTML. Therefore you must do your js_include definitions before libraries/header.inc.php is executed.

So adding js_include definitions in libraries/tbl_properties.inc.php is too late in the sequence. Instead, add them in a high-level file like tbl_alter.php and tbl_create.php.