Multiple checkboxes in razor (using foreach)

I have a big problem and I can't find solution. I'm using Razor and it is my VieModel class.

public class GroupToExport
{
    public GroupToExport()
    {
        ToExport = false;
    }

    [DisplayName("Export")]
    public bool ToExport { get; set; }
    public Group Group { get; set; }

}

public class GroupsToExport
{
    public GroupsToExport()
    {
        //refill list
    }

    public List<GroupToExport> ExportingGroups { get; set; }
}

View:

@using (Html.BeginForm("Export", "ElmahGroup", FormMethod.Post, new { id = "toExportForm" }))
{
//some divs
    <input type="submit" id="js-export-submit" value="Export" />
 @foreach (var item in Model.ExportingGroups)
                {
                    <tr>
                        <td class="js-export-checkbox">
                            @Html.CheckBoxFor(modelItem => item.ToExport)
                        </td>
                    </tr>
                }
//some divs
}

Controller:

public ActionResult Export(GroupsToExport model)
    {
        var groupsToExport = model.ExportingGroups.Where(x => x.ToExport).Select(x => x);
        throw new System.NotImplementedException();
    }

After submit "ToExport", in Controller, every group always has value 'false'. Even if all groups are checked.

Can somebody help me? What I'm doing wrong?