Silverlight.and CRM 2011

I've created a Silverlight webresource, For this reason, I've imported this service

http://xxxxxx:8088/CRM/XRMServices/2011/Organization.svc

but when, I want to create a OrganizationRequest, i have this error

Error 1 Cannot apply indexing with [] to an expression of type 'Con.CrmOrganization.OrganizationRequest' C:\SilverlightApplication\Activity.xaml.cs 42 13 SilverlightApplication

Can anybody help me?