@foreach (var item in ViewBag.nextClassesList)
{
    <tr class="@item.Status">
        <td>@item.ClassDate</td>
        <td>@item.User_Class.User1.NickName ? @item.User_Class.User.NickName   </td>
        <td>@item.User_Class.ClassType.ClassTypeName.Name (@item.User_Class.ClassType.ClassTypeName.Time min)</td>
    </tr>
}

<td>@item.User_Class.User1.NickName ? @item.User_Class.User.NickName   </td>


<td>@item.User_Class.User1.NickName </td> Is null sometimes...