Manually adding a vCard to Sabre CardDAV

[webscopeny]

We have installed Sabre on Centos 7 and it's working well

We're trying to manually add a contact to Sabre. I know this may be frowned upon, but after looking at the libraries, I feel we have it figured out. The only problem is that Thunderbird Address Book isn't syncing the newly added card. Any help would be appreciated

Sample created vCard saved as variable $carddata:
(We also tried converting the vCard to Version 3.0)

BEGIN:VCARD
VERSION:4.0
PRODID:-//Sabre//Sabre VObject 4.2.2//EN
UID:sabre-vobject-6909c955-72b1-4eae-8400-231b611d7b64
EMAIL:[email protected]
FN:John Smith
TITLE:President
END:VCARD

** Define fields:

$size=strlen($carddata)
$etag=md5($carddata)
$uri="$etag.vcf"

** Insert fields into "cards" table:

addressbookid: 1
carddata: $carddata
uri: $uri
lastmodified: Now
Size: $size

** Get synctoken field $synctoken from "addressbooks" record

** Insert fields into table "addressbookchanges":

uri: $uri
synctoken: $synctoken
addressbookid: 1
operation: 1

** Increment synctoken by one (synctoken=synctoken+1) in addressbooks table