Airprint doesn't work with a photosmart 5520

My iPad, iPhone 4s and HP Photosmart 5520 are connected with a KPN Experia Box v8 (dutch).

They can all use the internet, but im not able to send a print with the ipad/iphone to the photosmart.

the iphone/ipad can't find a printer when i use the command "select a printer".

The internet provider tolded me that i have to open some ports in the router firewall, but i don't know which one.

Can anyone help me?