Error converting data type varchar to bigint in stored procedure

I am trying to call this procedure using a command usp_TimesheetsAuditsLoadAllbyId 42747, NULL

.

But I always get the error

Msg 8114, Level 16, State 5, Procedure usp_TimesheetsAuditsLoadAllById, Line 9
Error converting varchar to bigint data type.

A ID

table table TimesheetsAudits

is a type bigint

. I've tried several types of conversions and castings, but I'm really stuck right now.

Hope someone can help. thank

ALTER PROCEDURE [dbo].[usp_TimesheetsAuditsLoadAllById]
(
    @Id INT,
    @StartDate DATETIME
)
AS
BEGIN
   SET NOCOUNT ON

   SELECT TOP 51 * 
   FROM 
      (SELECT TOP 51 
          ID,
          Type, 
          ReferrerId,
          CAST(Description AS VARCHAR(MAX)) AS Description,
          OnBehalfOf,
          Creator,
          DateCreated 
       FROM 
          TimesheetsAudits 
       WHERE 
          (ReferrerID = @Id) AND
          (@StartDate IS NULL OR DateCreated < @StartDate)
       ORDER BY
          DateCreated DESC

       UNION

       SELECT TOP 51 
          tia.ID,
          tia.Type, 
          tia.ReferrerId,
          '[Day: ' + CAST(DayNr AS VARCHAR(5)) + '] ' + CAST(tia.Description AS VARCHAR(MAX)) AS Description,
          tia.OnBehalfOf,
          tia.Creator,
          tia.DateCreated 
       FROM 
          TimesheetItemsAudits tia
       INNER JOIN 
          TimesheetItems ti ON tia.ReferrerId = ti.ID
       WHERE 
          (ti.TimesheetID = @Id) AND
          (@StartDate IS NULL OR tia.DateCreated < @StartDate)
       ORDER BY 
          tia.DateCreated DESC) t
   ORDER BY 
       t.DateCreated DESC
END

      

        
        
        
      

    

Defining a table for tables from comments:

CREATE TABLE [dbo].[TimesheetsAudits]( 
  [ID] [bigint] IDENTITY(1,1) NOT NULL, 
  [Type] [tinyint] NOT NULL, 
  [ReferrerId] [varchar](15) NOT NULL, 
  [Description] [text] NULL, 
  [OnBehalfOf] [varchar](10) NULL, 
  [Creator] [varchar](10) NOT NULL, 
  [DateCreated] [datetime] NOT NULL
)



CREATE TABLE [dbo].[TimesheetItemsAudits]( 
  [ID] [bigint] IDENTITY(1,1) NOT NULL, 
  [Type] [tinyint] NOT NULL, 
  [ReferrerId] [varchar](15) NOT NULL, 
  [Description] [text] NULL, 
  [OnBehalfOf] [varchar](10) NULL, 
  [Creator] [varchar](10) NOT NULL, 
  [DateCreated] [datetime] NOT NULL
)