The model item passed into the dictionary is of ty

Question

I'm new to asp.net and this is my first application. I'm developing an application that manages insurance requests. The model Request contains a file upload. the addDemand (adds a request)requires a member(adherent) to be logged in. Every time I try to run the addDemande I get the error:

The model item passed into the dictionary is of type 'System.Collections.Generic.List`1[Mutuelle.Domain.Entities.Demande]', but this dictionary requires a model item of type 'Mutuelle.Domain.Entities.Demande'.

Here's the controller:

 public ActionResult AddDemande()
        {
            Demande demande = new Demande();
            return View(demande);

        }


[HttpPost]
public ActionResult AddDemande([Bind(Exclude = "fichier")]Demande demande, HttpPostedFileBase fichier)
{
    try
    {
        if (!ModelState.IsValid)
        {
            return View();
        }
        else
        {
            BinaryReader fichierReader = new BinaryReader(fichier.InputStream);
            byte[] fichiers = fichierReader.ReadBytes(fichier.ContentLength);

            demande.fichier = fichiers;

            AdherentDService adherentService = new AdherentDService();
            Adherent adherent = (Adherent)Session["logedAd"];
            demande.nomBeneficiaire = adherent.nom;
            demande.eMailBeneficiaire = adherent.eMail;
            demande.beneficiare = adherent;
            adherent.listDemandes.Add(demande);
            adherentService.Updateadherent(adherent);
            demande.beneficiare = adherent;
            adherentService.CreateaDemande(demande);

            Session.Remove("logedAd");
            Session.Add("logedAd", adherent);
            return RedirectToAction("Demandes");

        }
    }

    catch
    {
        return RedirectToAction("Index", "Home");
    }

}

And here's the View:

 model Mutuelle.Domain.Entities.Demande

@{
    ViewBag.Title = "AddDemande";
}

<h2>AddDemande</h2>

@using (Html.BeginForm("AddDemande", "Adherent", FormMethod.Post, new { @enctype = "multipart/form-data" }))
{
    @Html.AntiForgeryToken()

    <div class="form-horizontal">
        <h4>Demande</h4>
        <hr />
        @Html.ValidationSummary(true)


        <div class="form-group">
            @Html.LabelFor(model => model.Nomrubrique, new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Nomrubrique)
                @Html.ValidationMessageFor(model => model.Nomrubrique)
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.fichier, new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                <input style="margin-left:0px;cursor:pointer;" type="file" name="fichier" id="fichier" />
            </div>
        </div>