Execute multiple commands in one line through ssh starting with pkill -f

Noticed something strange while working with a raspberry pi. Using pkill with no options allows me to run other commands afterwards in the same line, but if I use the option -f, then subsequent commands are ignored. Does anyone know why? $ ssh pi@192.168.1.1 "pkill -f blablabla ; echo yeaaaah" pi@192.168.1.1's password: $ ssh pi@192.168.1.1 "pkill blablabla ; echo yeaaaah" pi@192.168.1.1's password: yeaaaah It makes no difference whether process blablabla exists or not.