I haven't used this program in years, but from what I read here, you must install x11vnc and execute the following command before launching vnc2swf:

You can find more about this error (and possible solutions) here.

Regards.

This is also a good program for desktop recording:

http://recordmydesktop.sourceforge.net/about.php

There's also a front-end for it:

gtk-recordmydesktop

Thnx for reply I'll try them

Just an alternative here.
You can record a screen session from the command line with ffmpeg. To any format.

An example that I use
will tell you what to change to get it recording video and audio to the formats you wish.
(keep in mind, you have to have the relevant codecs installed)

apt-get install xvidcap
for open software - $ xvidcap
Now expand red rectangular area and start recording. File will be stored in root.
OR
Recording by ffmpeg
********************
ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 30 -s 1440x900 -i :0.0 -acodec pcm_s16le -vcodec libx264 output.avi
To stop Recording press q

for no mouse
ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 30 -s 1440x900 -i :0.0+nomouse -acodec pcm_s16le -vcodec libx264 output.avi

for recording any particular window, find window's co-ordinates & location
xwininfo | grep -e Width -e Height -e Absolute
ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 30 -s 650x500 -i :0.0+x,y -acodec pcm_s16le -vcodec libx264 output.avi
where 650x500 size of window & x,y coordinates of where you click to find details.

I had xcapvid it records on my computer 7frames per second, later I cannot change it with kdenlive