New stain on old deck turning grey upon application

Hi
I live in Southern CA. We bought a house with a deck that has has been pretty neglected. The wood is okay but hasnt been stained in a few years. It does get full sun. We power washed it a couple of weekends ago and now are starting to apply Sikkens translucent stain. Some of the areas of stain are very dark grey to black. It looks awful. What are we doing wrong?
Thanks for any help
Zma