C# 分析错误，以及错误的页面结果

我正在做这个简单的教程，我有这个问题。结果是错误的

url处的页面更改为2，但页面仍显示第1页，共2页

“下一个”和“上一个”不会更改结果

当我包含第二个else时，它会在“@:>>”上显示解析错误

下面是我的视图和控制器部分

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加载页面时链接的第二个代码第9行的currentFilter是什么？我试图用断点跟踪它，它没有显示任何值。我使用了断点并添加了watch，很抱歉，但可能不擅长此操作。。我在尝试：（叹气）

page @(Model.PageCount < Model.PageNumber ? 0 : Model.PageNumber)
of @Model.PageCount
@if (Model.HasPreviousPage)
{
    @Html.ActionLink("<<", "Index", new {
        page = 1,
        sortOrder = ViewBag.CurrentSort,               
        currentFilter = ViewBag.CurrentFilter })

@Html.Raw(" ")

@Html.ActionLink("< prev", "Index", new {
    page = Model.PageNumber - 1,
    sortOrder = ViewBag.CurrentSort,
    currentFilter = ViewBag.CurrentFilter })
}
else
{
    @:<<
    @Html.Raw(" ")
    @:< prev
}

@if (Model.HasNextPage)
{
    @Html.ActionLink("> next", "Index", new {
        page = Model.PageNumber + 1,
        sortOrder = ViewBag.CurrentSort,
        currentFilter = ViewBag.CurrentFilter })

    @Html.Raw(" ")

    @Html.ActionLink(">>", "Index", new {
        page = Model.PageCount,
        sortOrder = ViewBag.CurrentSort,
        currentFilter = ViewBag.CurrentFilter })
}
else
{
    @:> next
    @Html.Raw(" ")
    @:>>
}
</div>

public ViewResult Index(string sortOrder, string currentFilter, string SearchString, int? page)
{  
    ViewBag.CurrentSort = sortOrder;
    ViewBag.NameSortParm = string.IsNullOrEmpty(sortOrder) ? "Name Desc" : "";
    ViewBag.DateSortParm = sortOrder == "Date" ? "Date Desc" : "Date";
    var books = from b in db.Books select b;
    if (Request.HttpMethod == "Get")
    {
        SearchString = currentFilter;
    }
    else
    {
        page = 1;
    }
    ViewBag.CurrentFilter = SearchString;

    int PageSize = 3;
    int PageNumber = page ?? 1;
    return View(books.ToPagedList(PageNumber, PageSize));
}