I apologise if this has been addressed somewhere else, but I've been searching for a long time for a solution, so would rather make my own post with all of the details to maximise someone here being able to help me.
I have been trying to get Forge to work on my server - or, rather, for my Forge mods to work - but to no avail. I have tried everything I can think of; different ways of installing Forge, different places to put the mod .zip, have contacted my server host, the person who made the mod, and have been directed to programs that should - but haven't - help me.
The thing is, the server I am using is hosted by Veoserv.com - when I started using it, it had Bukkit installed. After contacting my host to get a solution for this, I discovered that from the control panel of my server I can revert back to vanilla entirely. This I did. No trace of Bukkit, no reason at all for Forge to not work as all those download tutorials say it should - but, still, I can't play my server modded.
Some information. I have been trying to install the "Biomes O Plenty" mod found on minecraftforum.net, and have briefly tried MystCraft as well. Both latest builds, and I have ensured to download the latest Forge builds as well. I install them as directed. Add the files in the Forge zip to the jar, deleting the META-Inf folder, and then putting the zip file of the mod into my mods folder. From what everyone else says, and from my own experience with single player, this should work, even on a "vanilla" server.
However, what I keep getting is the error, "Forge has found mismatched world IDs" or something to that effect, and then proceeds to list the item IDs and details of all of the custom blocks the mod includes. Again, I've tried this with multiple mods, so it isn't restricted to just one.
In the rare occasion that the server has allowed me to actually access the world its created, sure enough, none of the items from the "Biomes O Plenty" mod are in the world. As you can imagine, this has lead to strange looking terrain. Yet, on flying around the world, it's obvious that the biome mod has actually done something, because on hitting F3 I can view the (correct) names of the custom biomes, despite them not having anything in them. So, it seems that it's just the objects and textures that won't install to my game.
Some more info. I was told that "BukkitForge" would help when installing forge to a Bukkit server. That didn't work. I have also tried the MCPC Port, but due to the mod itself not having been ported this obviously led me to a dead end.
But, as I said, I have managed to revert my server back to pure vanilla, aside from one thing that doesn't seem changeable: the name of the .jar file, which is always "craftbukkit.jar", despite the contents being what you would find in a minecraft_server.jar. Yet, still I can't get this to work.
So, now, I am unsure as to what is the problem; my server, some kind of Bukkit residue that won't go away, or Forge itself. I have asked the modder, and my server hosts, so all that's left is to ask those who know more about Forge than I do. If I can't figure this out, I fear I'll either have to change hosts, or put up with paying for a service that isn't providing what I want. Neither of which I would like to do.
If anyone can help me at all, then I would be extremely grateful. I am at my wits' end here.