odd error...

CREATE TABLE tmp3 (

datname VARCHAR(255),
title VARCHAR(100),
artist VARCHAR(100),
album VARCHAR(100),
mp3checksum CHAR(32),
CONSTRAINT md5
    FOREIGN KEY (mp3checksum)
    REFERENCES tcontent (mp3checksum)
    ON DELETE CASCADE
);

NOTICE:  CREATE TABLE will create implicit trigger(s) for FOREIGN KEY
check(s)
ERROR:  UNIQUE constraint matching given keys for referenced table
"tcontent" not found

what am I doing wrong here?