[OpenLayers-Users] problem with overview map

[vrbikdan]

Hi,
I have a little problem with overview map. Simply, it doesn't show, what it 
should :). I have map of one region in the Czech Republic but overview map 
show me somewhere in the middle of ocean and I can't pan with overview map. 
I'm using google maps for base layers and it starts when I set 
sphericalMercator: true. Do you anyone know solution? Code is simple and here:

map.addControl(new OpenLayers.Control.OverviewMap({
div: document.getElementById('prehledkaContainer')}));

or it is here: http://dvphoto.xf.cz/dp/dp.html

Thanks a lot
Dan