EXECUTE permission denied - 'aspnet_Roles_Role

I am installing an application (BlogEngine) in a virtual directory under the main website, using SQL Server (MSSQLBlogProvider). BlogEngine has it's own database.

All worked, meaning I got the default page served from the SQL Database.

Then I used the ASP.net website administration tool\Security to create users (like shown in this video http://www.nyveldt.com/misc/BE13SQLMembership.html around the 7 minute mark. Very well explained and it's easy and fast to see what he is doing if you click around the timeline of the video)

After following those steps I get the error:

The EXECUTE permission was denied on the object 'aspnet_Roles_RoleExists', database 'Blog', schema 'dbo'. I to play around with the Access Rules but with no success.

Note that I am using "integrated security".

I'm not exactly shure whre to look and where to make modifications. Any help is hightly appreciated.

Stack Trace:

[SqlException (0x80131904): The EXECUTE permission was denied on the object 'aspnet_Roles_RoleExists', database 'Blog', schema 'dbo'.]
   System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction) +388
   System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose) +688
   System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady) +4403
   System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) +6665097
   System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite) +6667096
   System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite) +577
   System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite) +735
   System.Data.SqlClient.SqlCommand.ExecuteNonQuery() +290
   System.Web.Security.SqlRoleProvider.RoleExists(String roleName) +967
   System.Web.Security.Roles.RoleExists(String roleName) +336
   BlogEngine.Core.Right.InitRightForBlogInstance() in j:\Projects\BlogEngine_2_7_0_0\blogengine_4f5eed923a57\BlogEngine\BlogEngine.Core\Security\Right.cs:612
   BlogEngine.Core.Right.get_RightsByRole() in j:\Projects\BlogEngine_2_7_0_0\blogengine_4f5eed923a57\BlogEngine\BlogEngine.Core\Security\Right.cs:600
   BlogEngine.Core.Right.EnsureBlogInstanceDataLoaded() in j:\Projects\BlogEngine_2_7_0_0\blogengine_4f5eed923a57\BlogEngine\BlogEngine.Core\Security\Right.cs:566
   BlogEngine.Core.Right..cctor() in j:\Projects\BlogEngine_2_7_0_0\blogengine_4f5eed923a57\BlogEngine\BlogEngine.Core\Security\Right.cs:113

[TypeInitializationException: The type initializer for 'BlogEngine.Core.Right' threw an exception.]
   BlogEngine.Core.Right..ctor() in j:\Projects\BlogEngine_2_7_0_0\blogengine_4f5eed923a57\BlogEngine\BlogEngine.Core\Security\Right.cs:539

[TargetInvocationException: Exception has been thrown by the target of an invocation.]
   System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0
   System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +159
   System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +256
   System.Activator.CreateInstance(Type type, Boolean nonPublic) +127
   System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, StackCrawlMark& stackMark) +14376269
   System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) +200
   System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture) +28
   System.Web.HttpRuntime.CreateNonPublicInstance(Type type, Object[] args) +83
   System.Web.HttpApplication.BuildIntegratedModuleCollection(List`1 moduleList) +335
   System.Web.HttpApplication.GetModuleCollection(IntPtr appContext) +1262
   System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +133
   System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +304
   System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +404
   System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +475

[HttpException (0x80004005): Exception has been thrown by the target of an invocation.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +12881540
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +159
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +12722601

Open Internet Information Services Manager
Check what Application Pool your IIS Website is using
Go to Application Pools
See what Identity your App Pool is running under

Open SQL Server Management Studio
Connect to your SQL Server instance
Open a New Query for your database
Run this SCRIPT:
GRANT SELECT, EXECUTE, UPDATE, INSERT ON SCHEMA :: dbo TO
[NT AUTHORITY\NETWORK SERVICE]

*Replace [NT AUTHORITY\NETWORK SERVICE] with whatever Identity your App Pool is running as.

Go back to IIS Manager
Recycle your App Pool
Browse to your website