Subject Masterlinks demo - does not work ?

Trying to learn about masterlinks. Want to set up master table with
links to several other detail tables. Some detail tables will only
have one record linked, other could have multiple records linked.
When I delete entry from master table want all detail records also to
be deleted. As far as I can tell, masterlinks demo should do this
but when I try to delete a record from the master table I get an
error about Violation of Foreign Key Constraints.

Can someone point me in the right direction to learn how to
accomplish this.