مبتدی: مرتب سازی حبابی

سلام
من این الگوریتم رو برای مرتب سازی حبابی نوشتم اما در قسمت Button_click این خطا رو میده.

Error BC30455 Argument not specified for parameter 'aArray' of 'Public Function Exchange(aArray As Object) As Integer()'.

ممنون میشم راهنماییم کنید.

Public Class Form2 Private unsortlist As New Sort
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
unsortlist.Exchange()
End Sub
Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
End Class
Public Class Sort
Public Property aArray As Integer() = {5, 34, 12, 56, 2, 4, 12, 78, 90, 22, 1, 43}
Public Function Exchange(aArray) As Integer()
Dim i, j, temp As Integer
Dim flag As Integer = 1
For i = 11 To 0 Step -1
flag = 0
For j = 0 To j < i Step +1
If aArray(j) > aArray(j + 1) Then
flag = 1
temp = j
aArray(j) = aArray(j + 1)
aArray(j + 1) = temp
End If
Next
Next
Exchange = aArray
End Function
End Class