空引用异常VB

Question

VB.net的新手，沮丧的一直在关注这一天，为什么PbAlly（）值是什么？

我的剧情片：

Null Reference Exception error

代码如下：

Public Class Form1
Dim thdUDPServer
Dim Playing As Boolean = False
Dim Giliran As Boolean = False

Dim PbAlly() As PictureBox = {pbAlly1, pbAlly2, pbAlly3, pbAlly4, pbAlly5, pbAlly6, pbAlly7}

Dim Kartu As Integer = 0

Public Sub initGame()
    Dim RandomClass As New Random()
    Dim RememberSet As New HashSet(Of Integer)

    Dim RandomNumber As Integer

    While RememberSet.Count < 7
        RandomNumber = RandomClass.Next(1, 14)
        If RememberSet.Add(RandomNumber) Then
            If RandomNumber = 11 Then
                lbData.Items.Add("*J")
            ElseIf RandomNumber = 12 Then
                lbData.Items.Add("*Q")
            ElseIf RandomNumber = 13 Then
                lbData.Items.Add("*K")
            Else
                lbData.Items.Add("*" & RandomNumber)
            End If
            PbAlly(Kartu).Image = Card.My.Resources.ResourceManager.GetObject(RandomNumber)
            Kartu += 1
        End If
    End While
End Sub

PbAlly()总是给我一个空参考例外，我不知道为什么？

感谢您的帮助。