EXECUTE permission denied - 'aspnet_Roles_RoleExists' - asp.net

Question

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) [phone]
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) [phone]
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +159
System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) [phone]

Answer 1

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