Proper Formatting of Laravel DB Query

For some reason, I must be missing something when I am trying to move my query from raw SQL to Laravel DB.

At the moment, with this SQL query:

SELECT id, COUNT(id) AS count FROM agent_billings_items WHERE agentBillingBatch = 224 AND shipmentID IS NOT NULL GROUP BY shipmentID HAVING COUNT(id) > 1;

I get three (3) results back with the count return set correctly. However, when I try and write this out using Laravel DB:

    $results =  DB::table('agent_billings_items')
        ->select('id', DB::raw('count(*) as count'))
        ->where('agentBillingBatch', $this->id)
        ->whereNotNull('shipmentID')
        ->whereNull('deleted_at')
        ->groupBy('shipmentID')
        ->havingRaw('count > 1')
        ->get();

I get nothing returned. I know the raw SQL query is correct as I have manually checked it, so I know the $results in Laravel should come back with something.

I'd appreciate any help. Thanks

via Chebli Mohamed