IQueryable<MessageOutbound> query = from mo in this.All() where !mo.IsSending && mo.RemainingRetryCount > 0 select mo;

query = query.Where(mo => mo.DateLastAttempt.Value.Add(interval) <= DateTime.Now.ToUniversalTime());

Unsupported where clause: (mo.DateLastAttempt.Value.Add(TimeSpan:(00:01:00)) <= DateTime:(2012-05-31T12:06:09.2683135Z)). 
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.ArgumentException: Unsupported where clause: (mo.DateLastAttempt.Value.Add(TimeSpan:(00:01:00)) <= DateTime:(2012-05-31T12:06:09.2683135Z)).

Stack Trace: 


[ArgumentException: Unsupported where clause: (mo.DateLastAttempt.Value.Add(TimeSpan:(00:01:00)) <= DateTime:(2012-05-31T12:06:09.2683135Z)).]
   MongoDB.Driver.Linq.SelectQuery.BuildQuery(Expression expression) in C:\work\10gen\mongodb\mongo-csharp-driver\Driver\Linq\Translators\SelectQuery.cs:862
   MongoDB.Driver.Linq.SelectQuery.BuildQuery(Expression expression) in C:\work\10gen\mongodb\mongo-csharp-driver\Driver\Linq\Translators\SelectQuery.cs:827
   MongoDB.Driver.Linq.SelectQuery.Execute() in C:\work\10gen\mongodb\mongo-csharp-driver\Driver\Linq\Translators\SelectQuery.cs:132
   MongoDB.Driver.Linq.MongoQueryable`1.GetEnumerator() in C:\work\10gen\mongodb\mongo-csharp-driver\Driver\Linq\MongoQueryable.cs:81
   System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) +382
   System.Linq.Enumerable.ToList(IEnumerable`1 source) +80
   Datavod.Core.Repositories.MessageOutboundRepository.GetNext(TimeSpan interval, Int32 blockSize) in N:\Development\datavod\datavod.core\Repositories\MessageOutboundRepository.cs:84
   Datavod.Core.Services.MessageService.GetNext(TimeSpan interval, Int32 blockSize) in N:\Development\datavod\datavod.core\Services\MessageService.cs:25
   Datavod.Core.BackgroundService.SendMessages.Run() in N:\Development\datavod\datavod.core\BackgroundService\SendMessages.cs:41
   Datavod.Core.BackgroundService.InProcessBackgroundServiceExecutor.Start() in N:\Development\datavod\datavod.core\BackgroundService\InProcessBackgroundServiceExecutor.cs:46
   Datavod.Core.Infrastructure.BootStrapperTasks.LoadBackgroundServices.Execute(IDictionary`2 state) in N:\Development\datavod\datavod.core\Infrastructure\BootStrapperTasks\LoadBackgroundServices.cs:40
   datavod.web.MvcApplication.Application_Start() in N:\Development\datavod\datavod.web\Global.asax.cs:128

[HttpException (0x80004005): Unsupported where clause: (mo.DateLastAttempt.Value.Add(TimeSpan:(00:01:00)) <= DateTime:(2012-05-31T12:06:09.2683135Z)).]
   System.Web.HttpApplicationFactory.EnsureAppStartCalledForIntegratedMode(HttpContext context, HttpApplication app) +4057141
   System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +191
   System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +352
   System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +407
   System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +375

[HttpException (0x80004005): Unsupported where clause: (mo.DateLastAttempt.Value.Add(TimeSpan:(00:01:00)) <= DateTime:(2012-05-31T12:06:09.2683135Z)).]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11700896
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +141
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4869125