NEW ORLEANS, Feb. 27 ??? Mardi Gras revelers along St. Charles Avenue and Canal Street Monday night and over the weekend whooped for the marching bands, hollered for celebrities such as Dan Aykroyd, applauded the lavish floats and cried out for the trappings and trinkets tossed by costumed riders as they had for decades, but behind all the merriment and the masks something was missing.