A unit can EITHER support OR move.

In your example, you had ordered both units to provide support, and you had not ordered either of the units to make a move.

To make a move with support, one unit needs to move, and one or more other units need to support it.

A more correct set of orders might look like this:

# The army at Serbia move to Rumania.
# The army at Budapest support move to Rumania from Serbia.

Does this help?

Well, the failure of the first was because Budapest didn't try to move (it issued a suport move instead). The failure of the second was the same. You should have issued one of them to move, and the other to support it.

http://www.wizards.com/avalonhill/rules/diplomacy.pdf is the official rules for the game of Diplomacy and should answer most of your questions about the basics. The rest of the posters here on the forum (myself included) will be happy to help with the more esoteric issues. One thing to note: keep questions in as generic a form as possible if about an ongoing game, and never ever reference an ongoing game by putting a link to it on the forum. This is considered bad form.

Some things in general:
Gunboat = this is a game with NO textual communication (no chats, nothing on the forums, no PMs).
Public/Global Press Only = Only press that every one can see is allowed. This may be in game (usually, nowadays) or here on the forum (some oldschool games use the forum before the days of the chat log).
Anonymous = You won't know who the other players are and it is frowned upon to try and figure it out for the purposes or metagaming. although some variants, the fun is in guessing who the other players are.

Common screwups by noobs.
Support hold can only support a unit not attmepting to move. Convoying, holding, support move, and supporting hold are all hold orders and the unit in question can be support held. Issuing a move order, even if it fails, will break the support and leave the unit vulnerable.

Support move must refer to a moving unit.

Read the manual and ask more questions to your hearts content.

I was typing that all up while you put the quick one up, jamie. <grin>.

but i thougth and read that in the rules as well, that i can support another player as well? So why do i have to move if i just want to support someone else?

Then you should support from where the other player was.

Yes you can support another player's move. In which case you should order:

# The army at <insert location of your army> support move to <the place being moved to> from <the starting point of the other player's unit>.

Ok?

Alright, starts to make sense to me now :-) thanks to all of you, i appreciate your help...

Regards

You should definitely read the official rules that Draugnar posted the link to. Here is the link again:

http://www.wizards.com/avalonhill/rules/diplomacy.pdf

It doesn't take too long to get through them and it will greatly help your understanding of how the game works. If you don't you are going to run into one thing after another.

http://lmgtfy.com/?q=diplomacy+rules