Problem logging in to Office 365 Sharepoint Online from Webole hosted in the cloud

Hi,

I have a problem logging in to the Office 365 Sharepoint Online from a WebRole hosted in the cloud.
I have a WebService that logs in a user to Sharepoint Online as described in this post:
http://www.wictorwilen.se/Post/How-to-do-active-authentication-to-Office-365-and-SharePoint-Online.aspx

When starting my application with the cloud emulator in Visual Studio 2010, everything works fine.
When uploading the WebRole to my Azure Account, i get the following message:

Meldung: Unhandled Error in Silverlight Application Invoke operation 'GetGroups' failed. The remote server returned an error: (403) Forbidden.  at System.Net.HttpWebRequest.GetResponse()
  at Microsoft.SharePoint.Client.SPWebRequestExecutor.Execute()
  at Microsoft.SharePoint.Client.ClientContext.EnsureFormDigest()
  at Microsoft.SharePoint.Client.ClientContext.ExecuteQuery()
  at BTC.WFC.Dashboard.RiaServices.Web.UserInformationService.GetGroups(String username) in D:ProjekteSVN runkCORE_DevelopmentWFC-DashboardsrcDashboardServicesBTC.WFC.Dashboard.RiaServices.WebUserInformationService.cs:line 35
  at GetGroups(DomainService , Object[] )
  at System.ServiceModel.DomainServices.Server.ReflectionDomainServiceDescriptionProvider.ReflectionDomainOperationEntry.Invoke(DomainService domainService, Object[] parameters)
  at System.ServiceModel.DomainServices.Server.DomainService.Invoke(InvokeDescription invokeDescription, IEnumerable`1& validationErrors)
  at System.ServiceModel.DomainServices.Hosting.InvokeOperationBehavior.OperationInvoker.InvokeCore(Object instance, Object[] inputs, Object[]& outputs)

Is there any restriction or is there some configuration stuff that must be different when using the service in the cloud?

Kind regards,
Maik