They look like they were overexposed and/or overdeveloped. It's hard to tell which. When you get a plate like that you are close, but try cutting the exposure by about a stop or so. Make sure you have restrainer in your developer in hot weather, don't leave the plate in too long, you it will "blow out" and look flat. They'll look better when varnished, if you use Sandarac. If synthetic, they don't darken much at all.