SQL Server 2008 Using RANK to Dynamically Number R

Question

I have a stored procedure that pulls data for a SS Report. I need to include a Row Number column but I have never used RANK before and I'm gettig this error: Column 'WL.SSN' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.. Can anyone help me with the syntax? Here is what I have so far.

    SELECT
        WL.SSN,
        WL.LastName,
        WL.FirstName,
        WL.AddressLine1,
        WL.AddressLine2,
        WL.AddressLine3,
        WL.City,
        WL.State,
        WL.ZipCode,
        WL.Plus4,
        S.SeminarID,
        S.SeminarType,
        RANK = Count(*)                     
    FROM 
        @tblWaitList WL
        INNER JOIN @tblSeminar S ON WL.SeminarGuid=S.SeminarGuid
    WHERE
        S.SeminarID = @SeminarID AND S.SeminarType = @SeminarType
        AND RowNumber = COUNT(*)    
    ORDER BY
        RANK

I have tried almost every approach to this from http://support.microsoft.com/kb/186133 but I'm missing something.

Here is an example of what I'm trying to acheive...

 Rank        Au_Lname              Au_Fname
 ----        --------------        -----------
 1         Bennet                Abraham
 2         Blotchet-Halls        Reginald
 3         Carson                Cheryl
 4         DeFrance              Michel
 5         del Castillo          Innes
 6         Dull                  Ann
 7         Greene                Morningstar
 8         Green                 Marjorie

Answer 1

This should do:

SELECT rank() OVER (ORDER BY WL.LastName, WL.FirstName) as rank, WL.LastName, WL.FirstName 
FROM  @tblWaitList WL         
INNER JOIN @tblSeminar S 
ON WL.SeminarGuid=S.SeminarGuid     
WHERE S.SeminarID = @SeminarID AND S.SeminarType = @SeminarType         
ORDER BY rank ;