"MODEL" Does not contain a definition for “PROPERTY” and no extension method 'PROPERTY ' accepting a first argument of type 'MODEL' could be found

Question

View:

@model IEnumerable<models.AppModel> 
@using (Html.BeginForm()){
    <table>
    <tr>
        <td>
            @Html.LabelFor(model => model.Age) //error
</td>
</tr>
</table>
}

Controller:

public ActionResult Index(){
    if (string.IsNullOrWhiteSpace(unitCode))
            {
                return View(entity.dBSet.ToList());
            }
    else // do something else
}

Model:

namespace models{
    public class AppModel{
        public short Age {get; set;}
        public string Nationality {get; set;}
    }
}

In the view, every property of the model class such as Model.Age, Model.Nationality has this error. How do I fix it?