Tables and callbacks

Hi, I'm new to ACL and am having trouble understanding tables and callback functions. I intend to add some tags to a recently inserted table. My first step is to add my callback function for any document  to be invoked after inserting a table:

doc_add_callback(0, table_insert_after, myCB)

Unfortunately, it seems like the code within myCB is never run. No errors when adding myCB and no messages when inserting a table in the editor. Anyone knows why this is happening?

Thanks in advance,