Routing problem or? Works in epi 10 but not in epi 7

I have a solution that works in Episerver 10 but it doesnt work in Episerver 7. We have a customer who wants his solution in Episerver 7.

I have a controller with the name DigitalanslagstavlaPageController. This controller has two action. Index och GetDocument.
Index list information in the html view. GetDocument read a document from a webservice.

I get a list from action Index. It works.

I create a link to a document with

It creates a link that looks like this http://localhost:37008/DBB7Page/GetDocument/?Id=517

When i press the link i want to get the document from the webservice and go to a html view that show this document

This work in Episerver 10, but not in Episerver 7.

I get
Server Error ‘/’ Application
Content with id 517 was not found
*
*

You have the stack trace last

I know that the document with id exist in the database. I know that my back-end code works to.

I think it is a routing problem. Can anyone give me tips on how to solve the problem

This is my controller

public class DigitalanslagstavlaPageController : PageController<DigitalanslagstavlaPage>
{

    [HttpGet]
    public ActionResult Index(DigitalanslagstavlaPage currentPage)
    {
      /*  CODE THAT DO STUFF */
     return View(currentPage);
    }

    [HttpGet]
    public ActionResult GetDocument(DigitalanslagstavlaPage currentPage, int? Id)
    {
           /*  CODE THAT DO STUFF */
        return View(currentPage);
    }
}

My MVC routing is
    public class EPiServerApplication : EPiServer.Global
    {
        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
        }

        protected override void RegisterRoutes(RouteCollection routes)
        {
            base.RegisterRoutes(routes);

            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
              "Default",
              "{controller}/{action}/{id}",
              defaults: new { controller = "DigitalanslagstavlaPage", action = "Index", id = UrlParameter.Optional });
        }
    }

STACK TRACE:

[ContentNotFoundException: Content with id 517 was not found]
   EPiServer.DataAccess.ContentDB.ThrowNotFoundException(ContentReference contentLink) +135
   EPiServer.DataAccess.ContentLoadDB.LoadContentInternal(ContentReference contentLink, Int32 languageBranchId, DbDataReader reader) +306
   EPiServer.DataAccess.<>c__DisplayClass1.<Load>b__0() +328
   EPiServer.Data.Providers.<>c__DisplayClass1`1.<Execute>b__0() +87
   EPiServer.Data.Providers.SqlDeadlockRetryPolicy.Execute(Boolean isInTransaction, Func`1 method) +142
   EPiServer.Data.Providers.SqlDatabaseHandler.Execute(Func`1 action) +303
   EPiServer.DataAccess.ContentLoadDB.Load(ContentReference contentLink, Int32 languageBranchID) +286
   EPiServer.DataAbstraction.ContentStore.Load(ContentReference contentLink, Int32 languageBranchID) +67
   EPiServer.DefaultContentProvider.LoadContent(ContentReference contentLink, ILanguageSelector languageSelector) +562
   EPiServer.Core.<>c__DisplayClassf.<LoadContentFromCacheOrRepository>b__d() +190
   EPiServer.Core.OptimisticCache`1.Read(String cacheKey, ReadAndCacheObject`1 readAndCacheObject) +794
   EPiServer.Core.ContentProvider.LoadContentFromCacheOrRepository(ContentReference contentreference, ILanguageSelector selector) +1088
   EPiServer.Core.ContentProvider.Load(ContentReference contentLink, ILanguageSelector selector) +75
   EPiServer.DataFactory.Get(ContentReference contentLink, ILanguageSelector languageSelector) +395
   EPiServer.DataFactory.Get(ContentReference contentLink) +168
   EPiServer.Web.Mvc.ExistingActionRouteConstraint.Match(HttpContextBase httpContext, Route route, String parameterName, RouteValueDictionary values, RouteDirection routeDirection) +265
   EPiServer.Web.Routing.ContentRoute.MatchConstraints(SegmentContext segmentContext, HttpContextBase context) +650
   EPiServer.Web.Routing.ContentRoute.GetRouteData(HttpContextBase httpContext) +670
   System.Web.Routing.RouteCollection.GetRouteData(HttpContextBase httpContext) +235
   EPiServer.Web.Routing.RouteCollectionExtensions.HandleRouteData(RouteCollection routes, HttpContextBase context) +68
   EPiServer.Global.DefaultDocumentHandling(Object sender, EventArgs e) +215
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +141
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +69