When using rpg-x 2.3 I don't see all of the textures are there files needed to show them all
Have you downloaded poseidon, poseidon_a, v2-poseidon_a ?
Try getting those maps Telex said from here:
http://www.iwantstudios.com/
I forgot to post up in here I got it working, I somehow accidentily deleted Posiedon_a