SSRS 2005: Return NULL Values in Report with Parameter
===

I have a parameter called @vConsultant, which I use in a stored procedure as well as in an SSRS report.  The parameter is a drop-down menu populated by this query:


    select distinct c.nameConsultant
    from dataTable d
    
    left join consultants c on d.nameConsultant= d.recID

"dataTable" is my main data table that stores the ID of the consultant.  Consultants is the table that stores the names.  

The issue:  In dataTable, the consultant is an optional field.  And, in the reporting, my users want to see not only those consultants they select in the SSRS drop-down, but also the NULL values (where the user didn't specify a consultant).  However, the "NULL" doesn't show up as a value in the drop-down menu in SSRS.

In the stored proc, when I want to return NULLS, I do it with my where clause.  So...my proc is:

    CREATE PROCEDURE [dbo].[spReportProc] 
    
    @vConsultant varchar(max) 
    
    AS
    
    
    BEGIN
    	--Get comma-delimited list of consultants to allow SSRS multi-value select.
    	Select @vConsultant = ',' + @vConsultant + ','
    
    	create table #Consultant
    		(
    			nameConsultant varchar(1000)
    		)
    	Insert Into #Consultant 
    	Select  nameConsultant
    	From consultants
    	Where @vConsultant Like  '%,' + nameConsultant ',%'
    	And classification = 'Implementation Consultant'
    	Group By nameConsultant
    
    
    	Select * From dataTable d
    
    	left join consultants c on d.nameConsultant= d.recID
    
    			
    	Where 
    	@vConsultant Is NULL Or @vConsultant Like '%,' + i.firstName + ' ' + i.lastName + ',%') 
    END

But specifying NULL in this manner doesn't get noticed in SSRS.  Is there a way to allow NULL values in SSRS without actually specifying a NULL as part of the SSRS drop-down?  I have tried selecting the "Allow Null" and "Allow Blank" check boxes in SSRS, but that isn't working either.  

Let me know if more clarification is needed.  Thanks!