How to get a Single Result

Hi
I used Silverlight 3 Last realease also I tried RIA Service, Its very nice
My question is How to get a 1 Value in message box for exampl in Adventureworks data in Contacts
I like to put Firstname in Textbox then Get a Emailaddress for this Guy in Message box?
Please Help
Than u

Hi
No Answer !

http://silverlight.net/forums/p/51671/135324.aspx

QueryName="GetEmployeesByGender" AutoLoad="True"> <riaControls:DomainDataSource.DomainContext> <domain:AdventureWorksDomainContext /> </riaControls:DomainDataSource.DomainContext> <riaControls:DomainDataSource.QueryParameters> <riaData:ControlParameter ParameterName="gender" ControlName="gender" PropertyName="SelectedItem.Content" RefreshEventName="SelectionChanged" /> </riaControls:DomainDataSource.QueryParameters>