Cant ping printer when address is static

hi guys,

i setup an hp 7500a printer on a network...it has wireless so i connected it to the ssid and had no problem
the problem is that the printer is on auto address, and every time the router gets turned on and off its sending a new address
and the laptops dont print to it.

when i set the IP address and subnet mask to a manual address i just cannot ping or connect to it
i have no understanding why...what are you ment to do in this situation

any help appreciated
PK