Why exporting MySQL blob to XML then importing it back doesn't get the same result?

[satriaf]

I have some photos (not big, only 8kb) in mysql database (in my desktop). the field type is blob. actually i want to export the table to xml file then upload it to my database website. but it failed. I try to mimic it by exporting the table to xml file then importing it back to another table (the table's structure is same). I can do it but i don't get the same photos (only some encoding text). Here is some pieces of code:

Exporting the table to xml :

FileStream fs = new FileStream(filename,FileMode.Create,FileAccess.Write,FileShare.None);
StreamWriter sw = new StreamWriter(fs,Encoding.ASCII);
ds.WriteXml(sw);  //write the xml from the dataset ds

Importing the xml to the dataset :

FileStream fs = new FileStream(filename,FileMode.Open);
DataSet ds = new DataSet();
ds.ReadXml(fs);

Writing the dataset to another table :

       ...
       int count = ds.Tables[0].Rows.Count;
       for(int i=0;i<count;i++)
       {  
           DataRow myDR = ds.Tables[0].Rows[i];
           ...
           byte[] myphoto = null;
           if(myDR["myphoto"].ToString().Length > 0)
           {
              myphoto = Encoding.ASCII.GetBytes(myDR["myphoto"].ToString().ToCharArray());
           }
           //insert the data to the mysql table 
           ...
       }
       ...

Why i don't get the same photos in this another table?
sorry for my bad english.