The problem seems to be that you are attempting to add a password when you have opted to enter a Pre-Shared Key(PSK). If you want to provide a password for decryption you need to enter it by selecting: Edit -> Preferences -> Protocols -> IEEE 802.11 -> New -> wpa-pwd
Also you'll need to tick the 'Enable decryption' box, plus you may need to play with the 'Assume packets have FCS' setting and clicking on Apply till you hopefully see the decrypted packets.
If want to capture packets from machines other than the one you're capturing on you may also need to play with the promiscuous mode setting - trying both on and off in monitor mode.