[Help] error "Failed to login vaultmp interface"

Hi! (sorry for my english i'm french :/)
So, My problem is when i click on "Join Server" an error message occured and it's: "Failed to login vaultmp interface" i relaunch vaultmp and my computer but vaultmp doesn't work :/

I need Some help please!

Did you put default.fos in your mygames folder?

@volumed: only the serversided default.fos is required isnt it?

No, i do not believe so i'm not sure for some people it fixes the no pip-boy problem but you can still join a server without it.. Never heard of this problem either..

Yes, the save is in Mygames folder and when i click on "Synchronize" it work but i can't login :/

Can't login in what? Get in a server? Did you create your own hamachi server?

Tell me how did you install it.

My friend create a hamachi, and i can't login at the server because error "failed to login vaultmp interface" comes. My friend use a server on which have to play Call of duty before

I don't believe it's a connecting problem so that Call Of Duty works is not important.

Questions:

1. For what game are you trying VaultMP?
2. The server works for your friend?
3. Did you try to install VaultMP again.
4. And how did you install it full details please did you change something like a .INI every little thing can be the problem.
5. Is your friend using mods or did he change a PAWN script.
6. Did he try to install VaultMP again?

1: Fallout 3
2: Yes it work
3: Yes!
4: I follow this tutorial https://www.youtube.com/watch?v=Zkd6RHExuR4
5: No
6: Yes

Created your own server and see if you still have the same problem.