Capturing WPA handshake problems

why can’t I get handshake most of the time using deauthentication attack? Or sometimes I get partial handshake messages like this one, I’m only getting message 1 and 3.
Is it because of my wireless adapter or something else? I’m using an adapter with chip rtl8812au.

Sometimes it is because of the router you got. Try to be as close to the router you can get. The problem can also be with your wifi adaptor. It is hard to debug usually for this. You have to keep trying.