What is the correct syntax for using EXCLUDE_SYMBOLS?

Question

I have a class like:

class Foo {
public:
  /** blah blah */
  void bar();
}

I want to exclude this from the documentation, but it EXCLUDE_SYMBOLSdoes not work for me. I tried the following (one by one):

EXCLUDE_SYMBOLS = Foo::bar
EXCLUDE_SYMBOLS = Foo::*
EXCLUDE_SYMBOLS = Foo
EXCLUDE_SYMBOLS = *

None of them work. Is there a mistake in my syntax or is there some other configuration that I need to change for this to take effect?

I reviewed a few questions about SO, but the syntax used in these answers does not work for me.