Problem with POIS

hello,

I made several POIS with the tutorial here http://wiki.openstreetmap.org/index.php/Openlayers_POI_layer_example .

My problem is now the POIS were displayed, but they are on a different position. When I zoom in then the pois slowly move to the right position. When I have reached the maximum zoom level than the POI is on the right position. Why is that. In the example from the site you can zoom in and out and the pois are almost at the right position.

with regards