Image Problem In Sql Server & Asp.net

Hi friends,
I am using ASP.NET (with C#) and SQL Server 2005 Express Edition.
I have to store images in database.
When I download the image from SQL, it gives exception 'Parameter is not valid.'
I check the size of the byte array and it is really not valid.
I store an image that has a size of 4991 bytes(as a byte array). But when I download it, it has only 13 bytes(byte array again).
This is my upload code :

MemoryStream ms = new MemoryStream();
System.Drawing.Image im = System.Drawing.Image.FromFile(Server.MapPath("Image\example.gif"));
Byte[] byteArray;
im.Save(ms, ImageFormat.Gif);
byteArray = ms.ToArray();

Here ms.Length is 4983 bytes not 4991! example.gif is 4991 bytes.

My SQL sentence :

"update reklamlar set Resim=" + byteArray + " where ReklamID=1;"

My download code :

byteArray = new byte[reader.GetBytes(4,0,null,0,int.MaxValue)];
mstream.Write(byteArray, 0, byteArray.Length);
System.Drawing.Image im = System.Drawing.Image.FromStream(mstream);

Here byteArray.Lenght is only 13!!!

Please help me what is wrong with this code?
Thanks a lot..

Note : In SQL management studio express, in the image area this text is written : <binary data>
It is 13 characters you see. May be there a relationship???