Description:
------------
If you call an instantiated object's private/protected method's via call_user_func_array(array($objFoo, 'bar'), $arrParams)

the error message regarding why the method is not callable is too generic. It implies the function does not exist.

Please note: This is NOT a bug in the code, but rather a error message that could definitely be more helpful, which is why it's filed under documentation.

Reproduce code:
---------------
<?php

class A {
	private function Foo() {
		return 'Foo!';
	}
}

$objA = new A();
call_user_func_array(array($objA, 'Foo'), array());

?>

Expected result:
----------------
Fatal error: Call to private method A::Foo() from context '' in on line 10

Actual result:
--------------
Warning: call_user_func_array(): First argument is expected to be a valid callback, 'A::Foo' was given in on line 10