Cannot Save A Long String

This is what I am trying to save and what is actually being saved:

All variables are STRINGS.

Saving: 08:02:40 08:18:05 ^09:34:07 09:39:25 ^10:02:50 10:18:19 10:37:33 11:01:34 11:23:26 11:50:47 ^12:52:30 13:42:37 ^14:41:04 ^18:36:13
Saved: 08:02:40 08:18:05 ^09:34:07 09:39:25 ^10:02:50 10:

Saving: 08:08:52 08:59:55 ^09:38:04 09:54:20 ^10:15:37 10:34:40 10:39:02 11:12:45 11:39:33 ^12:18:51 13:11:24 ^14:04:52 15:18:43 ^19:13:10
Saved: 08:08:52 08:59:55 ^09:38:04 09:54:20 ^10:15:37 10:

The codes:

Table scripted to a query:

USE [Analytical]
GO
/****** Object: Table [dbo].[DailyTickMinMaxAnalysis] Script Date: 08/07/2007 15:44:29 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[DailyTickMinMaxAnalysis](
[symbol] [varchar](50) NOT NULL,
[cDate] [varchar](50) NOT NULL,
[part] [varchar](50) NOT NULL,
[collection] [varchar](max) NULL,
CONSTRAINT [remPat_Trades] PRIMARY KEY CLUSTERED
(
[symbol] ASC,
[cDate] ASC,
[part] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF

Stored procedure is:

USE [Analytical]
GO
/****** Object: StoredProcedure [dbo].[InsertDailyTickMinMaxAnalysis] Script Date: 08/07/2007 15:45:49 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER OFF
GO

ALTER PROCEDURE [dbo].[InsertDailyTickMinMaxAnalysis]
@symbol varchar(50),
@cDate varchar(50),
@part varchar(50),
@collection varchar(50) = NULL
AS
BEGIN
SET NOCOUNT ON;
INSERT INTO dbo.DailyTickMinMaxAnalysis (
symbol,
cDate,
part,
[collection])
Values (
@symbol,
@cDate,
@part,
@collection)
END

C# procedure:
public void saveHistTickMinMaxAnalysis ( int tableIndex )
{
if ( tableIndex != -1 )
{
using ( SqlConnection conn_Analytical = new SqlConnection ( "server=ddmnvt61\sqlexpress;" +
"database=Analytical;Trusted_Connection=Yes" ) )
{
SqlCommand cmdm = new SqlCommand ( );
conn_Analytical.Open ( );
cmdm.Connection = conn_Analytical;
cmdm.CommandType = CommandType.StoredProcedure;
cmdm.CommandText = "InsertDailyTickMinMaxAnalysis";
cmdm.Parameters.Clear ( );
cmdm.Parameters.Add ( "@symbol", SqlDbType.VarChar, 50, "symbol" );
cmdm.Parameters.Add ( "@cDate", SqlDbType.VarChar, 50, "cDate" );
cmdm.Parameters.Add ( "@part", SqlDbType.VarChar, 50, "part" ); // 2
cmdm.Parameters.Add ( "@collection", SqlDbType.VarChar, 500, "collection" ); // 3
foreach ( DataRow row in Globals.dtSets.Tables[tableIndex].Rows )
{
cmdm.Parameters[0].Value = ( string )row[0];
cmdm.Parameters[1].Value = ( string )row[1];
cmdm.Parameters[2].Value = ( string )row[2];
cmdm.Parameters[3].Value = ( string )row[3];
Console.WriteLine ( "Saving {0}", ( string )row[3] ); // <= where the print out occurs to confirm that the right string is being passed
try
{
cmdm.ExecuteNonQuery ( );
}
catch { }
}
}
}
} // saveHistTickMinMaxAnalysis

Table is defined with the last columns[3].Length = 500;

What happened to the rest of my strings?

I would appreciate any help.

Many thanks.