SQLite no such table error when table exists in xamarin

This is How I define my table as what this link: SQLite no such table error when table exists said

[Table("RegUserTable")]
[Serializable]
[DataContract]
public class RegUserTable
{
    [PrimaryKey]
    [DataMember]
    public Guid UserId { get; set; }

    [DataMember]
    public string Username { get; set; }

    [DataMember]
    public string Password { get; set; }

    [DataMember]
    public string Email { get; set; }

    [DataMember]
    public string Gender { get; set; }
}

This is my Login code:

public void Button_Clicked_1(object sender, EventArgs e)//LOGIN!
{
    var dbpath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "Userdatabase.db");
    var db = new SQLiteConnection(dbpath);
    var loginquery = db.Table<RegUserTable>().Where(u => u.Username.Equals(EntryLoginUsername.Text) && u.Password.Equals(EntryLoginPassword.Text)).FirstOrDefault();

    if (string.IsNullOrWhiteSpace(EntryLoginUsername.Text) && string.IsNullOrWhiteSpace(EntryLoginPassword.Text))
    {
        DisplayAlert("Blank Fields", "Please Input Your Username and Password!", "OK");
    }
    else if (loginquery != null)
    {
        App.Current.MainPage = new NavigationPage(new MainPage(EntryLoginUsername.Text, GenderIdentifier.Text));
    }
}

If I run this in my emulator it works 100%, but when I run it on my device it throws this error:

What am I doing wrong here?

Creating the table something like below solves the issue

public async void Button_Clicked_1(object sender, EventArgs e)//LOGIN!
{
    var dbpath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "Userdatabase.db");
    var db = new SQLiteConnection(dbpath);

    var connection = new SQLiteAsyncConnection(dbpath); 
    await connection.CreateTableAsync<RegUserTable>();

    var loginquery = db.Table<RegUserTable>().Where(u => u.Username.Equals(EntryLoginUsername.Text) && u.Password.Equals(EntryLoginPassword.Text)).FirstOrDefault();

    if (string.IsNullOrWhiteSpace(EntryLoginUsername.Text) && string.IsNullOrWhiteSpace(EntryLoginPassword.Text))
    {
        DisplayAlert("Blank Fields", "Please Input Your Username and Password!", "OK");
    }
    else if (loginquery != null)
    {
        App.Current.MainPage = new NavigationPage(new MainPage(EntryLoginUsername.Text, GenderIdentifier.Text));
    }
}