A PDF is being received from an API but I cannot attach it to a record using code

Related to the topic, I have the following code, but this time I try to obtain the pdf from an api, and save it in Shipment, I show you the code and the error that appears:

[PXButton(CommitChanges = true)]
[PXUIField(DisplayName = "Track")]

protected void apiTracking()
{
    DownloadAndUploadFile();
}

public void DownloadAndUploadFile()
{
    try
    {
        using (HttpClient client = new HttpClient())
        {
            string url = "http://qaglp.paquetexpress.mx:8083/wsReportPaquetexpress/GenCartaPorte?trackingNoGen=19167736449";
            HttpResponseMessage queryResult = client.GetAsync(url).Result;

            if (queryResult.IsSuccessStatusCode)
            {
                byte[] fileContent = queryResult.Content.ReadAsByteArrayAsync().Result;

                UploadFile(fileContent, "downloadedFile55.pdf");
            }
            else
            {
                PXTrace.WriteWarning("HTTP request was not successful.");
            }
        }
    }
    catch (Exception ex)
    {
        PXTrace.WriteWarning("An exception occurred: " + ex.Message);
    }
}

private void UploadFile(byte[] file, string fileName)
{
    try
    {
        // Create an instance of PX.SM.UploadFileMaintenance
        PX.SM.UploadFileMaintenance uploadFileMaintenanceGraph = PXGraph.CreateInstance<PX.SM.UploadFileMaintenance>();

        // Create a FileInfo object for the file
        PX.SM.FileInfo fileInfo = new PX.SM.FileInfo(fileName, null, file);

        // Save the file
        if (uploadFileMaintenanceGraph.SaveFile(fileInfo, PX.SM.FileExistsAction.CreateVersion))
        {
            PXTrace.WriteInformation("File uploaded successfully.");

            // Associate the file with each shipment
            foreach (SOShipment shipment in Base.Document.Select().RowCast<SOShipment>().ToList())
            {
                // Upload the file and associate it with the shipment
                uploadFileMaintenanceGraph.SaveFile(fileInfo, PX.SM.FileExistsAction.CreateVersion);
                uploadFileMaintenanceGraph.AttachFile(typeof(SOShipment).FullName, shipment.ShipmentNbr, fileInfo);
            }
        }
        else
        {
            PXTrace.WriteWarning("Error uploading the file.");
        }
    }
    catch (Exception ex)
    {
        PXTrace.WriteWarning("An exception occurred: " + ex.Message);
    }
}
and I get this error:

[2024-03-05 18:21:11.673] \App_RuntimeCode\SOShipmentEntry.cs(164): error CS1061: 'UploadFileMaintenance' does not contain a definition for 'AttachFile' and no accessible extension method 'AttachFile' accepting a first argument of type 'UploadFileMaintenance' could be found (are you missing a using directive or an assembly reference?)