Unable to resolve column level collations

Question

This whole stored procedure is to generate a csv file into the mention folder where file is getting generated but the headers are missing.

--Adding missing headers into the file----
DECLARE @columnHeader VARCHAR(8000)
SELECT @columnHeader = 


'''RecordID'',''MSISDN'',''Amount'',''ReferenceID''
 ,''SessionID'',''Action'',''RequestDate'',''ResponseDate''
,''StatusID'',''Channel'',''CallBackRequestDate'',''CallBackResponseDate''
,''CallBackReferenceID'''


  Select @cmd = 'BCP '+'"Select '+ @columnHeader +' UNION ALL SELECT convert(varchar(20), 
  [RecordID]),convert(varchar(20),[MSISDN]),convert(varchar(20),[Amount]),convert(varchar(20), 
  [ReferenceID]),convert(varchar(20),[SessionID]),convert(varchar(20), 
  [Action]),RequestDate,ResponseDate,convert(varchar(20),[StatusID]),convert(varchar(20), 
  [Channel]),CallBackRequestDate,CallBackResponseDate,CallBackReferenceID From [LinkVisaCard].[dbo]. 
  [Transaction]"'+ ' QUERYOUT C:\TransactionsData\' +@fileName +' '+ '/c /t"|" /T'+@ServerName
  PRINT @cmd
  EXEC master..xp_cmdshell @cmd;

So I tried to use above query inorder to add missing headers where i am getting below error: error: SQLState = 22008, NativeError = 241 Error = [Microsoft][SQL Server Native Client 10.0][SQL Server]Conversion failed when converting date and/or time from character string. SQLState = S1000, NativeError = 0 Error = [Microsoft][SQL Server Native Client 10.0]Unable to resolve column level collations please do the needfull

   ALTER PROCEDURE [dbo].[GenerateCDR]
   AS
   Begin
   DECLARE @sqlCommand varchar(8000)
   DECLARE @filePath VARCHAR(125)
   DECLARE @fileName VARCHAR(125)
   DECLARE @todaysDateFormatted VARCHAR(30)
   DECLARE @ServerName varchar(50)

   -- generate the dynamic file name based on the date and time
   SELECT @todaysDateFormatted = CONVERT(VARCHAR, GETDATE(), 112) + '_' + CAST(DATEPART(HOUR, GETDATE()) 
   AS VARCHAR) + '_' + CAST(DATEPART(MINUTE,GETDATE()) AS VARCHAR) + '_' + CAST(DATEPART(SECOND, 
   GETDATE()) AS VARCHAR)
   -- ALTER the file name
   SET  @fileName ='Tansactions_'+  @todaysDateFormatted + '.csv';

   SET @ServerName = 'TRUSTACCTEST';

   DECLARE @cmd varchar(8000)

   -----Copy the table records into TransactionsData folder with .csv file----
   Select @cmd = 'BCP '+
   '"Select * From [LinkVisaCard].[dbo].[Transaction]"'
    + ' QUERYOUT C:\TransactionsData\' +@fileName +' '+ '/c /t"|" /T'+@ServerName
   PRINT @cmd
   EXEC master..xp_cmdshell @cmd;
   PRINT @cmd

   ------Adding missing headers into the file----------
   DECLARE @columnHeader VARCHAR(8000)
   SELECT @columnHeader = 
 '''RecordID'',''MSISDN'',''Amount'',''ReferenceID'',''SessionID'',''Action'',''RequestDate'',''ResponseD 
  
 ate'',''StatusID'',''Channel'',''CallBackRequestDate'',''CallBackResponseDate'',''CallBackReferenceID'''


      Select @cmd = 'BCP '+'"Select '+ @columnHeader +' UNION ALL SELECT convert(varchar(20), 
      [RecordID]),convert(varchar(20),[MSISDN]),convert(varchar(20),[Amount]),convert(varchar(20), 
      [ReferenceID]),convert(varchar(20),[SessionID]),convert(varchar(20), 
      [Action]),RequestDate,ResponseDate,convert(varchar(20),[StatusID]),convert(varchar(20), 
      [Channel]),CallBackRequestDate,CallBackResponseDate,CallBackReferenceID From [LinkVisaCard].[dbo]. 
      [Transaction]"'+ ' QUERYOUT C:\TransactionsData\' +@fileName +' '+ '/c /t"|" /T'+@ServerName
      PRINT @cmd
      EXEC master..xp_cmdshell @cmd;
      END