IIRC they said they were qos data packets.
I would bet a large amount of money that your network is a "protected" network, using either WEP or WPA/WPA2, which means that it uses encryption to protect against people trying to sniff the network, and that the packets in question have the "Protected" bit set in the link-layer header, meaning that they're encrypted.
This means that they cannot be dissected past the 802.11 layer unless they can be decrypted.
Therefore, you will need to, at a minimum, provide Wireshark with the password for the network. If it's a WPA/WPA2 network, you will also need to, after you start capturing, disconnect the baby monitor from the network and reconnect it, in order to force it to re-associate with the network, so that you capture the "EAPOL handshake" when it joins the network.
See the Wireshark Wiki page on decrypting 802.11 packets for more details.