membuat bilangan prima dari vb.net

Dim A, B, C As Integer
Private Sub PERIKSA_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PERIKSA.Click
A = Val(TXT1.Text)
If A < 2 Then TXT2.Text = "NOT PRIMA"
ElseIf A = 2 Then
TXT2.Text = "IS PRIMA"
Else
B = 2
Do
C = A Mod B
If C <> 0 Then
B = B + 1
Else
TXT2.Text = " NOT PRIMA"
B = B + A
End If
Loop Until B >= A
If A = B Then
TXT2.Text = "IS PRIMA"
End If


End If
End Sub
End class