delete & reinstall brand new virtual server => let's encrpt has issue

Hi,

I delete the old virtual server and create a brand new one on same subdomain. when i try to install ssl using let's encrypt, here is the message, not sure what to do?

Parsing account key... Parsing CSR... Registering account... Already registered! Verifying www.food.orderlastminute.com... Wrote file to /home/food/public_html/.well-known/acme-challenge/PYFSDZqnMUP5b7sC6mOObPxllSBAkr_K6DoPcHUBZY0, but couldn't download http://www.food.orderlastminute.com/.well-known/acme-challenge/PYFSDZqnM... Traceback (most recent call last): File "/usr/share/webmin/webmin/acme_tiny.py", line 203, in main(sys.argv[1:]) File "/usr/share/webmin/webmin/acme_tiny.py", line 199, in main signed_crt = get_crt(args.account_key, args.csr, args.acme_dir, log=LOGGER, CA=args.ca) File "/usr/share/webmin/webmin/acme_tiny.py", line 154, in get_crt domain, challenge_status)) ValueError: www.food.orderlastminute.com challenge did not pass: {u'status': u'invalid', u'validationRecord': [{u'url': u'http://www.food.orderlastminute.com/.well-known/acme-challenge/PYFSDZqnM...', u'hostname': u'www.food.orderlastminute.com', u'addressUsed': u'', u'port': u'80', u'addressesResolved': None}], u'keyAuthorization': u'PYFSDZqnMUP5b7sC6mOObPxllSBAkr_K6DoPcHUBZY0.uuiElfoe4kOu7whVVQHElZ7oRwD7mNFdX2Xdds20qTI', u'uri': u'https://acme-v01.api.letsencrypt.org/acme/challenge/zdcw5CuViwzPt1ZpXyuw...', u'token': u'PYFSDZqnMUP5b7sC6mOObPxllSBAkr_K6DoPcHUBZY0', u'error': {u'status': 400, u'type': u'urn:acme:error:connection', u'detail': u'DNS problem: NXDOMAIN looking up A for www.food.orderlastminute.com'}, u'type': u'http-01'}