Solid stain over old stain

After cleaning with a cleaner/brightner and pressure washing a deck, there is some old stain adhering to the uprights. Sanding takes most of it off, but it will not allow the semi transparent stain to soak in. Can I use a solid stain on the verticals without stripping again? Does the solid stain need to penetrate to adhere? The brand I am using (Zar) says not to apply unless the surface will absorb water. Is there another brand that will adhere to the old finish? This is a second floor deck with a finished deck below, so stripping isn't an option.