Ol3 fail on the first pan (NaN, NaN)

I have a map on the link below:

http://ift.tt/1BSNTqK The map works well, however there is one thing what is frustrating me. When I load the page and the first thing what I try to do on the map is pan the map window change to white and the coordinates change to NaN, NaN. If I start with zoom in or out the map and the pan function work as well. Is there anybody who can provide me a solution?