wireless problems with compaq Evo n600c

Unfortunate, i have a big problem with the laptop "compaq Evo n600c".

in the last year, i have seen about 5 laptop of this model , and
everytime this laptop doesn't work with the signal of my wireless network.

i put the wireless PCMCIA card and it works.

yesterday, i saw a person with this laptop he was another place and it
was working there.

why it doesn't work in my wireless network signal.
the Different between my wireless network and the place i saw this laptop
working wireless in it , is the first has linksys APs and the second has
d-link APs.

anyonr have any idea?

thanks alot