Xamarin couchbase server and sync gateway not syncing

Question

In Xamarin, I am trying to sync the local database with sync gateway, but it is not syncing. I am trying it with sample https://github.com/couchbaselabs/mini-hacks/tree/master/kitchen-sync

Local database is getting updated but it is not syncing with sync gateway

I have provided the sync url:http://localhost:4984/sync_gateway/ Also updated config file

{
    "interface": ":4984",
    "adminInterface": ":4985",
    "log":["CRUD+", "REST+", "Changes+", "Attach+"],
    "databases": {
        "sync_gateway": {
        "server": "walrus:data",
        "bucket": "sync_gateway",
         "sync": `function(doc)
         {
             channel(doc.channels);
         }`,
         "users": {
             "GUEST": {
             "disabled": true,
             "admin_channels": [ "*" ]
         }
    }
}

On checking the data bucket, item count is not getting added up. Can anyone help me out.