I'll have to look up what / where the purge valve is. Had lines at canister replaced because they were cracked and could actually hear them leaking. Haha
Not sure if the cracks seen in the pictures following are related to the EVAP system or are even big enough to cause the P0455. The first pic is to show the general area. The second, if you look close towards the bottom where it connects into the engine, both of those lines have a small crack.
Let me know if you can see or not. I uploaded this from my phone. If its hard to see I can blow it up and highlight when I get to the computer.