When "replicate_do_db" and "replicate_wild_do_table" both specified,both options will be invalid

In a slave I just want to replicate two types of database from master, so I use following SQL to replicate mydb1 and mydb2, but result is no database is been replicated!

STOP SLAVE;

SET GLOBAL replicate_do_db = "mydb1";

SET GLOBAL replicate_wild_ignore_table = "mydb2.tb%";

START SLAVE;