Floats -> SideBar does not work in left or right float

Hello,

I'v got some sidebars in my docBook document. Now I try to transformate it to pdf. It works well with not left or right argument. The sidebar is placed in the middle. The result should be some boxes with on the left outer side.
But if I set the left or right the sidebar is not in the pdf....

Should the master page layout have a special layout? I set it to the A4 -> are there any Region-start and Region-end?
-> page.margin.outer, mage.magin.inner ???

Thank you a lot of :-)

Kind regards
Martin