DevDefined - Get QBO Invoices and Deserialize response

protected IEnumerable<Invoice> GetInvoicesWithOpenBalance(DataServices dataServices, int startPage, int resultsPerPage)
    {
        try
        {
            Intuit.Ipp.Security.OAuthRequestValidator oAuthRequestValidator = ((Intuit.Ipp.Security.OAuthRequestValidator)dataServices.ServiceContext.RequestValidator);

            OAuthConsumerContext consumerContext = new OAuthConsumerContext
            {
                ConsumerKey = oAuthRequestValidator.ConsumerKey,
                SignatureMethod = SignatureMethod.HmacSha1,
                ConsumerSecret = oAuthRequestValidator.ConsumerSecret
            };

            OAuthSession oSession = new OAuthSession(consumerContext, "https://www.example.com",
                                    "https://www.example.com",
                                    "https://www.example.com");

            oSession.AccessToken = new TokenBase
            {
                Token = oAuthRequestValidator.AccessToken,
                ConsumerKey = oAuthRequestValidator.ConsumerKey,
                TokenSecret = oAuthRequestValidator.AccessTokenSecret
            };

            var body = "PageNum={0}&ResultsPerPage={1}&Filter=OpenBalance :GreaterThan: 0.01";
            body = String.Format(body, startPage, resultsPerPage);

            IConsumerRequest conReq = oSession.Request();
            conReq = conReq.Post().WithRawContentType("application/x-www-form-urlencoded").WithRawContent(System.Text.Encoding.ASCII.GetBytes(body)); ;
            conReq = conReq.ForUrl(dataServices.ServiceContext.BaseUrl + "invoices/v2/" + dataServices.ServiceContext.RealmId);
            conReq = conReq.SignWithToken();

            Intuit.Ipp.Data.Qbo.SearchResults searchResults = (Intuit.Ipp.Data.Qbo.SearchResults)dataServices.ServiceContext.Serializer.Deserialize<Intuit.Ipp.Data.Qbo.SearchResults>(conReq.ReadBody());
            return ((Intuit.Ipp.Data.Qbo.Invoices)searchResults.CdmCollections).Invoice;

        }
        catch (Exception)
        {

            return null;
        }

    }