Docking toolbars

Hi,
on first start of my program I have my toolbars loaded from a cui file (all floating and invisible). After that I want to dock some of them in different rows and columns using the IAcadToolbar class. The command Dock(acToolbarDockTop) works fine, but put_top(n) and put_left(0) seem to have no effect: the toolbars are always added to the first row.
Am I doing something wrong?

Thanks.