流量控制和图片框

Question

我无法成功运行程序，这是我的VB代码：

Private Sub PictureBox2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox2.Click 

Dim a As Object
a = PictureBox1.Image
Dim b As Object
b = PictureBox2.Image
If a = b Then
    TextBox1.Text = "plz try again~"
Else
    TextBox1.Text = "good jod!"
End If

我希望程序运行如下： 当picturebox1中的图像与我单击的图片框相同时，文本框将显示“well down” 但如果不是，文本框将显示“请再次尝试”，但显示错误：Operator '=' is not defined for type 'Bitmap' and type 'Bitmap'.