Can't add some US ANSI Shifted Symbols (e.g. " (KC_DOUBLE_QUOTE); _ (KC_UNDERSCORE))

[Oyren]

First of all, thanks for your development. As the title says, i can't find a way to add the " (KC_DOUBLE_QUOTE) and _ (KC_UNDERSCORE) symbols to my layer.
I also tried it via the ANY button in the SPECIAL group, but entering the keycodes results in a grayed-out confirmation button.