If you mean shaking while using it, that could be normal if you're using a small tablet area.
However what's not normal is shaking or moving on it's own.
Try updating your driver to the latest version, and if you really think it's an issue from your tablet, not you, you could try this:
- Press the windows key+R, a run box will pop up, type there "services.msc.
- Scroll down until you see "Wacom Professional Service".
- Right click it and click "Start", if it's already running click "Restart".