System.IO.FileNotFoundException

I am getting System.IO.FileNotFoundException when referencing the dll from a SharePoint 2013 Event Receiver: Could not load file or assembly 'Aspose.Pdf, Version=10.2.0.0, Culture=neutral, PublicKeyToken=6947866647e416ec' or one of its dependencies. The system cannot find the file specified.

Please let me know what additional information you need to assist with this issue.

Here is the code:

public class PDFUpdaterTestReceiver : SPItemEventReceiver
{
    /// <summary>
    /// An item was added.
    /// </summary>
    public override void ItemAdded(SPItemEventProperties properties)
    {
        base.ItemAdded(properties);

        if (properties.ListTitle == "Documents")
        {
            SPSecurity.RunWithElevatedPrivileges(delegate
            {
                using (SPSite site = new SPSite(properties.WebUrl))
                {
                    using (SPWeb web = site.OpenWeb())
                    {
                        try
                        {
                            //get list item
                            SPList list = web.Lists[properties.ListId];
                            SPListItem item = list.Items[properties.ListItem.UniqueId];
                            SPFile file = item.File;
                            MemoryStream myStream = new MemoryStream();
                            byte[] bf = file.OpenBinary();
                            MemoryStream ms = new MemoryStream(bf);

                            //Aspose PDF Classes - get and modify document links
                            Document document = new Document(ms);
                               
                            foreach (Aspose.Pdf.Page page in document.Pages)
                            {
                                //get links for the current page
                                AnnotationSelector selector = new AnnotationSelector(new LinkAnnotation(page, Aspose.Pdf.Rectangle.Trivial));
                                page.Accept(selector);
                                IList linksList = selector.Selected;
                                  
                                //loop through links and update as needed
                                foreach (LinkAnnotation link in linksList)
                                {
                                    string linkURI = (link.Action as Aspose.Pdf.InteractiveFeatures.GoToURIAction).URI;
                                    if (linkURI.Contains("intranet.chop.edu"))
                                    {
                                        //need to update GoToURIAction
                                        link.Action = new Aspose.Pdf.InteractiveFeatures.GoToURIAction(linkURI + "?CHOP=atchop");

                                        //GoToRemoteAction goToR = (GoToRemoteAction)link.Action;
                                        // Next line update destination, do not update file
                                        //goToR.Destination = new XYZExplicitDestination(document, 2, 0, 0, 1.5);
                                        // Next line update file
                                        //goToR.File = new FileSpecification("c:/pdftest/PDFInput (1).pdf");
                                    }
                                }
                            }

                            //save document with updated links
                            //document.Save("c:/pdftest/ResultantFile.pdf");
                            document.Save(ms);

                            //update the list item
                            string linkFilename = file.Item["LinkFilename"] as string;
                            file.ParentFolder.Files.Add(linkFilename, ms, true);

                        }
                        catch (Exception ex)
                        {
                            properties.Status = SPEventReceiverStatus.CancelWithError;
                            properties.ErrorMessage = "Error : " + ex.Message;
                        }
                    }
                }
            });
        }
    }
}

Thanks.