There are 3 possible reasons for this to occur:

1) Cacheflow is unable to reach the CachePulse server on TCP_80 and TCP_443
- The Cacheflow uses it's own IP address to check and download the CachePulse update. Ensure that the Cacheflow IP is able to access cacheflow-list.es.bluecoat.com at TCP_80 and TCP_443


2) The Cacheflow does not have it's Appliance Certificate:
- Check if the Appliance Certificate is present:

Cacheflow 3x5#sh ssl keyring appliance-key
Keyring ID:               appliance-key
Private key showability:  no-show
Signing request:          present
Certificate:              present <-------- If this shows as absent, manually download it
Certificate issuer:       Blue Coat Systems, Inc.
Certificate valid from:   Jan 01 18:56:35 2015 GMT
Certificate valid to:     Jan 01 18:56:35 2020 GMT
Certificate thumbprint:   93:19:43:B0:38:E7:CC:32:1D:2B:74:C8:41:22:5C:FF
Cacheflow 3x5#

- If the Appliance Certificate is not "Absent", apply the following command to force a manual download:
     #conf t
     #(config)ssl
     #(config ssl)request-appliance-certificate

- The download would occur over TCP_443 from "abrca.bluecoat.com". Ensure the Cacheflow IP has access to the OCS

3) The Cacheflow's "Maintenance Status" is no longer "Active". Please engage Bluecoat Support to double-check