Installing new mods to pack?

[Randomite]

I'm trying to install some new metal sets from Metallurgy into the Big Dig pack (Nether and Fantasy) and I can't seem to get it to work. I just copy and paste the .jar files into mods, as instructed in it's (Metallurgy's) thread, but it doesn't affect the game at all. I can't seem to find anyone else who has this problem, so any help at all would be appreciated. Thanks.

EDIT: I have Optifine installed, if that causes any problems.

[miniboxer]

Did you generate a new world?

[Randomite]

Yes, I have, but the new metals don't exist in the game.

[advvtech]

Did you included the core in Mods? it doesn't go in coremods

[Randomite]

Core was already included in mods, along with precious metals and end metals.