WAP?
WAP stands for Wireless Access Point. All wireless networks are (well have a) WAP.
I presume from your "WAP protected" statment you mean either WEP or WPA... which are encrypted networks (though WEP is barely better than unencrypted but that doesn't matter for this)
I am afraid I may not be able to help you as I don't have a DS, but if you confirm what you mean it might help (and others may be able to help better)
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If it is a WEP or WPA encrypted network you are trying to connect to, then there must be a setting somewhere in the DS for inputting the password for it (presumably you had to input an SSID too?... can you give more details about the network)