If you are using the wordpress api to hook into actions or filters there are some pitfalls. But these pitfalls are not wordpress related but likely your faults. I wan’t to show how to NOT hook into wordpress. 1. add_action( “actionA”, array( __CLASS__, “processA”, 10, 3) ); Please check the array declaration. Stupid mistake, but it’s hard to locate the error. You can output $wp_filter and check if everything is in the right place:

[myClass::actionA] => Array
                        (
                            [function] => Array
                                (
                                    [0] => myClass
                                    [1] => processA
                                )

                            [accepted_args] => 3
                        )