新手求助！数据库更新问题！！

本人刚学习ASP.net ，做了个数据库通过GRIDVIEW更新数据的程序，问题是在VS里调试时可以更新，但是发布出来，在IE里面却无法更新，提示是“操作必须使用一个可更新的查询。”，代码如下：恳请各位解答！谢谢了！
public partial class _Default : System.Web.UI.Page 
{
    public void bind()
    {
        DataTable dt = new DataTable();
        OleDbConnection myconn = new OleDbConnection();
        myconn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\db\users.mdb;User Id=;Password=;";
        string sql = "select userid,username,password,enable,trycount from passwd order by username";
        OleDbDataAdapter adap = new OleDbDataAdapter(sql, myconn);
        try
        {
            myconn.Open();
            adap.Fill(dt);
        }
        catch (Exception)
        {
            
        }
        finally
        {
           myconn.Close();
        }
        
        GridView1.DataSource = dt;
        GridView1.DataKeyNames = new string[] { "UserID" };
        GridView1.DataBind();      
    }    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            
            bind();
        }                
    }
    protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        this.GridView1.PageIndex = e.NewPageIndex;
        bind();
    }    
    protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
    {
        GridView1.EditIndex = -1;
        bind();
    }
    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {        
        string username = ((TextBox)(GridView1.Rows[e.RowIndex].Cells[2].Controls[0])).Text.ToString().Trim();
        string passwd = ((TextBox)(GridView1.Rows[e.RowIndex].Cells[3].Controls[0])).Text.ToString().Trim();
        bool  enable = ((CheckBox)(GridView1.Rows[e.RowIndex].Cells[4].Controls[0])).Checked;
        string trycount = ((TextBox)(GridView1.Rows[e.RowIndex].Cells[5].Controls[0])).Text.ToString().Trim();
        int flag;
        if (enable == true)
        {
            flag = 1;
        }
        else
        {
            flag = 0;        
        }
        string sql = "update passwd set [Username]= '"+username+"',[password]='"+passwd+"',[enable]='"+flag+"',[trycount]='"+trycount+"' where [UserID]=" + Convert.ToInt16(GridView1.DataKeys[e.RowIndex].Value.ToString()) + "";
        OleDbConnection myconn = new OleDbConnection();
        myconn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\db\users.mdb;User Id=;Password=;";
        OleDbCommand command = new OleDbCommand(sql, myconn);
        try
        {
            myconn.Open();
            command.ExecuteNonQuery();
        }
        catch (Exception ex)
        {
            Response.Write(ex.Message);
        }
        finally
        {
            myconn.Close();
        }
        GridView1.EditIndex = -1;
        bind();
    }        protected void GridView1_RowEditing1(object sender, GridViewEditEventArgs e)
    {
        GridView1.EditIndex = e.NewEditIndex;
        bind();    
    }
    
}