求1000以内的完数，求大神看看这么写哪里错了

顶

Private Sub Form_Click()
Dim a As Long, b As Long, c As Long, d As Long
For a = 2 To 1000
For b = 1 To a - 1
If a Mod b = 0 Then c = c + b
Next b
If a = c Then
Print a
End If
Next a
End Sub

来人啊