Can not "COPY FROM" with Postgres & Python

As the topic, this is the code and there is no error message but data did not get insert. This is my code, and can anyone tell me what's wrong with it?

import psycopg2import sysimport osimport glob import csv#open the csv folderdictfile='******'os.chdir(dictfile)total=[]for file in glob.glob("*.csv"):    total.append(file)con = Nonetry:     con = psycopg2.connect(host='localhost',database='*****',user='postgres', password='*****')     cur = con.cursor()    for i in range(0,1):           filename='/Users/Shared'+'/'+total[0]        print filename        #better move all files into shared folder        x="copy public.crossref_sample from "+"'"+filename+"'"+" DELIMITERS ',' CSV"        print x        cur.execute(x)  except psycopg2.DatabaseError, e:    print 'Error %s' % e        sys.exit(1) finally:    if con:        con.close()