Greetings,
I've found that the 'uzi' object from zexy cannot be created unless (the identical but verbosely-titled) 'kalashnikov' has been previously created during the pd session. FWIW, I'm using pd-0.37-3 (latest stable build from Miller's site), WinXP, zexy-nt-1.3 (I'm not aware of a more recent version), along with various other libs.