I've attached a form that will do what you require. Please double-check the spelling to make sure I got it all right.
To use the form, do the following:
Dim frm As New frmMsgbox(Me.Text, "Limit Kredit Tidak Cukup ...!", dblSisaPiutang, dblSisaSOBelumKirim, dblSisaSOBelumFaktur, dblSOBaru, dblLimitKredit)
frm.ShowDialog()
Let me know if you need any more help with this.