I would like to use orderBy in laravel but its not working while I have used CAST there

    $this->adLists = ListingVisitor::with('listing')->selectRaw('CAST(sum(amount) as UNSIGNED) as total,listing_id,amount')->whereHas('listing.user',function($q){
        $q->where('id',Auth::user()->id);
    })->groupBy('listing_id')->orderBy('total','DESC')->paginate(10);

The result would be

136, 66, 1 ,5

Its actually should be 136, 66, 5, 1

I have using CAST in selectRaw but it has no difference