Dynamic Order By and ASC DESC

Referencing: stackoverflow.com/questions/1147763/dynamic-order-direction

I attempted to set mine up the same way, but I'm receiving the error message: Conversion failed when converting the varchar value 'StartDate' to data type int.

The below is what I have:

@OrderBy varchar(10) = 'StartDate',
@Direction int = 1

...
      CASE WHEN @Direction = 0 THEN 1
      ELSE
            CASE WHEN CAST(@OrderBy AS varchar(10)) = 'StartDate' THEN 'StartDate'
                  WHEN CAST(@OrderBy AS varchar(10))  = 'EndDate' THEN 'EndDate'
            END
      END ASC,
      
      CASE WHEN @Direction = 1THEN 1
      ELSE
            CASE WHEN CAST(@OrderBy AS varchar(10)) = 'StartDate' THEN 'StartDate'
                  WHEN CAST(@OrderBy AS varchar(10))  = 'EndDate' THEN 'EndDate'
            END
      END DESC