Hi CHIO!
Either you're on windows or linux follow this recipe:
0) Un-install the current Synfig Studio version you have. Remove the ~/.synfig folder (if in linux) or the User Folder/Synfig folder (if in windows). That will prevent to remember any previous settings.
1) Download and install the latest release 0.62.01:
http://synfig.org/en/current-release It should solve the problem form the start. Do it even if you already have it installed. For windows it will give you much better performance than the last release. The default settings will be set again.
2) If the above doesn't work, please follow this recipe:
2.1) Disable all the extended input devices from the Input devices dialogue (Toolbox->File->Input Devices...). All them.
2.2) Test if you can click and drag the ducks with the mouse (not the tablet, the mouse). It should work.
2.3) Then enable the Wacom device that is listed in the device settings diaglog that correspond to your tablet. Enable only one first. Test it with the tablet. Be sure you have it set to Screen not to Window.
2.4) If you have more devices (i.e. eraser) try to enable them in the same way and test after enable it.
Some people has experienced problems with the device and just enable and disable and enable it again solves the problem.
I think it is not a problem of Synfig because the code that gets the extended input devices comes from the gtk libraries to handle them.
-G