I thought the following would work to group by hours by it is not:

SELECT CONVERT(CHAR(4),YEAR(Hit.AddDate))+REPLACE(STR(MONTH(Hit.AddDate),2),' ','0')+
REPLACE(STR(DAY(Hit.AddDate),2),' ','0')+REPLACE(STR(HOUR(Hit.AddDate),2),' ','0') AS lcChampNumero,
COUNT(*) AS Compte,MIN(Hit.AddDate) AS AddDate 
FROM Hit (NOLOCK) 
 GROUP BY CONVERT(CHAR(4),YEAR(Hit.AddDate))+REPLACE(STR(MONTH(Hit.AddDate),2),' ','0')+
 REPLACE(STR(DAY(Hit.AddDate),2),' ','0')+REPLACE(STR(HOUR(Hit.AddDate),2),' ','0') ORDER BY 1 DESC 

The Hour is not a recognized built-in function name.

What can I do?