Brookie.
There may be some reasons why you did not get fish to take when fishing dead drift.
Which may be related to choice and size of flies and presentation, which would include length of leader. Typically l will use a longer leader when fishing this way with 5x and may be 6 at times depending on fly size.
Look at it like this, if the fish take the fly dead drift they do so because it looks like a natural food source tracking downstream. If they take it on the swing they do so due to the movement, all be it here will be certain flies that will trigger a better response at times.
Therefore, in the case of upstream use flies that are more imitative, a Peter Ross would not be in this category, but it may be the anchor fly l use to control the two flies above it, such as spiders and soft hackles.
PP Your goodies are on the way.
Davy.