[1.6.4][Coremod] Using ResourceLocation in coremod

I try to use ResourceLocation to load resource in coremod. Resource domain have no space nor capital letter. My code work fine in eclipse but not in the game. I've searched through the forum and googling and found someone with the same problem here http://www.minecraftforge.net/forum/index.php?topic=10316.0

but got no answer.

So I put up a new topic. What am I doing wrong? Please help.

ResourceLocation init:

private static final ResourceLocation thaifont = new ResourceLocation("fdbported_client_core","textures/thai.png");

My jar structure:

client_core.jar

--> META-INF

----> MANIFEST.MF

--> _fdb

----> fdbported_core_client

------> **All codes go here**

--> assets

----> fdbported_client_core

------> textures

--------> thai.png