Can read whisper files using whisper-fetch but can't display on graphite web

Hi,

[Environment]
I have deployed Graphite using Gunicorn web server and Nginx proxy server. Gunicorn and Nginx are on different machines.
I am using collectd to collect system metrics. The collectd is pushing data to Graphite gunicorn's host. The data is getting stored correctly and when I execute this command `whisper-fetch.py storage/whisper/collectdip-<ip-address>_us-west-1_compute_internalcollectd/memory/memory-free.wsp --pretty`, it's showing that it is collecting the most recent data.

However, I am not able to display it on Graphite's web console.

Here are my local settings.py
SECRET_KEY = '<secret-string>'
ALLOWED_HOSTS = <>
TIME_ZONE = 'America/Los_Angeles'
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': '<db_name>',
        'USER': '<db_user>',
        'HOST': '<db_host>',
        'PORT': '<db_port>'
    }
}

#####################################
# Email Configuration #
#####################################
#
# This is used for emailing rendered graphs. The default backend is SMTP.
EMAIL_HOST = '<email_host>'
EMAIL_HOST_USER = '<email_user>'
EMAIL_HOST_PASSWORD = '<email_key>'
EMAIL_PORT = <email_port>
EMAIL_USE_TLS = True

#####################################
# Filesystem Paths #
#####################################
GRAPHITE_ROOT = '/opt/graphite'
CONF_DIR = '/opt/graphite/conf'
STORAGE_DIR = '/opt/graphite/storage'
CONTENT_DIR = '/opt/graphite/webapp/content'
DASHBOARD_CONF = '/opt/graphite/conf/dashboard.conf'
GRAPHTEMPLATES_CONF = '/opt/graphite/conf/graphTemplates.conf'
WHISPER_DIR = '/opt/graphite/storage/whisper'
RRD_DIR = '/opt/graphite/storage/rrd'
DATA_DIRS = [WHISPER_DIR, RRD_DIR] # Default: set from the above variables
LOG_DIR = '/opt/graphite/storage/log/webapp'
INDEX_FILE = '/opt/graphite/storage/index' # Search index file

Can anyone please help me here? Thanks in advance.