you supply very little information! a lot of things can be the cause of this.
you should gather some logs on the hand-held and on the AP to find some clues.
but mostly you need to look for security and compatibility.
because this is an old device first check if the both speak the same language (use the same wi-fi protocols.
I guess the hand-held supports the 802.11b protocol (maybe b/g)
and the AP speaks 802.11 n/ac -> those will not be compatible