Hello

In the SSRS interface for parameter input, how can I send Null for a parameter value? 

Thanks a lot.

see this helps http://en.csharp-online.net/Building_Reports_in_SQL_Server_2005%E2%80%94Setting_Report_Parameters_with_Stored_Procedures 

Note that when you supply NULL as the parameter, and your sproc has a default value for that parameter, then the default value will not be used. Defaults for parameters only kick in when the parameter is not mentioned when the sproc is called.