SPexception group cannot be found

I am trying to add users to a group through people picker. When i run it, SPgroup returns null and it throws an error saying group cannot be found. I have tried with both SPweb context and SPsite with and without SPsecurity. New developer, thanks for any advice.

public void Button6_Click(object sender, EventArgs e)
        {
   
            if (PeopleEditor1.Accounts.Count > 0)
            {
                PickerEntity pe = (PickerEntity)PeopleEditor1.Entities[0];
                string username = pe.Description;
                string group = DropDownList2.SelectedItem.Text;
                addUserToGroup(group, username); 
            }
            else
            {
                Label3.Text = "Please insert and validate a user in people picker.";
                PeopleEditor1.SetFocus();
            }
        
        }              

        public void addUserToGroup(string groupName, string userLoginName)
        {
            SPSecurity.RunWithElevatedPrivileges(delegate()
            {

                SPSite site = new SPSite(Page.Request.Url.ToString());
                SPWeb web = site.OpenWeb();   
          //    SPWeb web = SPContext.Current.Web; 
                web.AllowUnsafeUpdates = true;
                SPUser spUser = web.EnsureUser(userLoginName);
                SPGroup spGroup = web.Groups[groupName];

                if (spUser != null && spGroup != null)
                {
                    spGroup.AddUser(spUser);

                }