Unable to ping from CE router to CE router

I have just started leaning MPLS. The problem is I am unable to ping the Loop back interface on CE router from another CE router, even though it is showing up in the routing table. I am suspecting that the Cause for this could be due to next-hop IP address in the provider core. However, I am not sure how to fix it.

Kindly help. here is the topology, it is actually from another blog from Rene him self. I have. Please find the config of my PALM , MELON , PE & P routers. I have not watched the solution yet as I dont want to spoil the rest of the lab. If i can get this passed I believe I can complete the rest of it.

PE2.txt (3.2 KB)
P Router.txt (1.5 KB)
PALM HQ.txt (1.2 KB)
PALM BRANCH.txt (1.3 KB)
PE1 ( R3 ).txt (2.8 KB)

The issue might be the source of the ping, in that the destination does not have a return route (this depends on what you have configured for networks advertised in RIP).

Have you tried issuing your ping, but ensuring it is sourced from the loopback?