数据库插值问题

提示： VS2005 并不报错 也就是没有语法错误  
可是数据库中没有插入的数据，设置断点编译表明reVale 的值为0
也就是说 reVale = db.sqlEx(cmdstr); 调用方法出现问题


 protected void btnRegister_Click(object sender, EventArgs e)
    {
        int reVale = CheckName();
        if (reVale == 1)
        {
            Response.Write(db.MessageBox("该用户存在，请重新设置！", "Register.aspx"));
        }
        else
        {
            string UserName = this.txtUserName.Text;
            string PassWord = this.txtPwd.Text;
            string Emial = this.txtEmail.Text;
            string cmdstr = "insert into tb_User(UserName,PassWord,Emial)Values('" + UserName + "','" + PassWord + "','" + Emial + "')";
            try
            {
                reVale = db.sqlEx(cmdstr);
                if (reVale == 1)
                {
                    Response.Write(db.MessageBox("注册成功！", "Register.aspx"));
                    Clear();//清空文本框
                }
                else if (reVale == 0)
                {
                    Response.Write(db.MessageBox("注册失败!", "Register.aspx"));
                }
            }
            catch
            {
                Response.Write(db.MessageBox("注册失败!", "Register.aspx"));
            }
        }
    }


public int sqlEx(string cmdstr)
    {
        SqlConnection con = new SqlConnection(connstring);
        con.Open();
        SqlCommand cmd = new SqlCommand(cmdstr, con);
        try
        {
            cmd.ExecuteNonQuery();//执行这一句出现异常
            return 1;
        }
        catch (Exception e)
        {
            return 0;
        }
        finally
        {
            con.Dispose();
        }

    }