Then you possibly need to ask to your host what their limit is/to check it for you ;)
30 megabytes is a lot to upload using PHP, so they possibly limit it (also the .htaccess method).

But can you please upload a htaccess file, because I think, that I did something wrong. :o

Here you go ;)
It's in a zip, because vB.org doesn't allow uploading .htaccess files to the attachments.

But you really can't do anything wrong. If you put those two lines in a file and called it .htaccess, that's all. Then you just need to upload it to your forum directory and you are done.

i uploaded 2 files and it works well.

but now i allways get the message:

"The upload failed! Upload error."

and i dont know why.....

can you give me a hint plz where i have to seach for an answer

Is the extension on the list of allowed extensions (AdminCP -> Downloads -> Settings)?
Is it a large file (PHP has got an upload limit, look at this post for more information)?
Maybe you linked the previous files and you are now uploading one from your computer? So be sure the downloads directory is writable (777 chmod).
...

I have to say the support for this mod is one of the best ever! :)

its all as it sould be ........
in dont find the mistake :(

Strange, as it gives only that error if the move_uploaded_file PHP function failes to move the file to the downloads directory. You can get the error when the file is too large for PHP's upload limit, when you haven't done the chmod or when the function is on the forbidden functions list of your host (some hosts implements very strict/strange security things).

Are you running PHP in safe mode (you can see this on the home of your AdminCP)?

safe mode is off

If you try uploading a small file, does it work?