Android Question Change button by click on error

btn.Color = XUI.Colors_red

    btn.As(B4XView).Color = xui.Color_Red

Private Sub ButAnswer_Click
    Dim btn As Button = Sender
    Dim gd As ColorDrawable
    If AnsverNum = btn.Text Then
        gd.Initialize(Colors.RGB(92,161,58) , 10dip)
        btn.Background = gd
        Sleep(300)
        PlayGame
        Coine
        gd.Initialize(Colors.RGB(41,119,156), 10dip)
        btn.Background = gd
    Else
        gd.Initialize(Colors.Red,10dip)
        btn.Background = gd
        Error
    End If
End Sub

Private Sub nextQuestion
    Dim answer As Int = Rnd(0, 4)       ' Choose a random button hold correct answer
    Dim i As Int = 0
    For Each btn As Button In buttons   ' Set up choices in buttons
        ' In a real quiz incorrect answers would be used instead of "Wrong"
        If (i = answer) Then btn.Text = "Correct" Else btn.Text = "Wrong"
        btn.As(B4XView).Color = xui.Color_LightGray
        i = i + 1
    Next
End Sub

Private Sub btn_Click
    Dim btn As Button = Sender
    If (btn.Text = "Wrong") Then btn.As(B4XView).Color = xui.Color_Red
    For Each b As Button In buttons
        If (b.Text = "Correct") Then b.As(B4XView).Color = xui.Color_Green
    Next
    Sleep(3000)                          ' Delay to next question
    nextQuestion
End Sub