System.IO.FileLoadException with WebService

I'm using Visual Studio 2013 and I am trying to create a webservice using the assembly DNSTools from Nuance SDK. My WebMethod is really simple : I just create an object from a DNSTools' class, then return "Hello World".

using DNSTools;
namespace WebTestFinal
{
    public class WebServiceTestFinal : System.Web.Services.WebService
    {
        [WebMethod]
        public string HelloWorld()
        {
            DgnDictCustom dgn = new DgnDictCustom();
            return "Hello World";
        } 

However when I reach the line :

DgnDictCustom dgn = new DgnDictCustom();

It throws me this error :

System.IO.FileLoadException: Retrieving the COM class factory for component with CLSID {A0E850E3-91DB-11D1-96DC-0080C72FD13C} failed due to the following error: 8007045a. A dll initialization routine failed. (Exception of HRESULT : 0x8007045A).
 at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck)
 at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
 at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
 at System.Activator.CreateInstance(Type type, Boolean nonPublic)
 at System.Activator.CreateInstance(Type type)
 at WebTestFinal.WebServiceTestFinal.HelloWorld()

I did some research and found out that System.IO.FileLoadException was thrown because an assembly cannot be loaded. Despite using Fuslogvw.exe and Process Monitor I can't find which assembly is the root of the problem.

Go to Project Properties and in Build Tab, select X86 for platform target, and if it's already X86 change de to 64

In VS - project properties - in the Build tab - platform target =X86