Sidebar in Single Product Page

I’d like to add a sidebar to the single product page. I’ve created a new sidebar and set it in the product properties. The sidebar is always displayed after the product descriptions. I tried to change the layout options in the theme option, without success.
In the product properties I choosed the Layout&Sidebar option (Use selected layout and sidebar options) it has also no effect on the single product page.
I have already spent a couple of hours…
Has anyone a hint for me?