This is my first attemt w/ Outlook and I am using the
provided sample and the book "Microsoft Outlook
Programming. I have been using the sample project ItemsCB
as a base for creating my application.  I added a command
bar button to the MailItem Standard toolbar using this
code:

Set cb = Inspector.CommandBars.Item("Standard")

When that button is clicked, I want to launch a VB 6 form
I designed.  I created my Inspector wrapper class
following the ExplWrap class.  I instantiate my inspector
object as follows and use WithEvents:

Public Property Let Inspector(objInsp As Outlook.Inspector)
On Error Resume Next
  Set m_objInsp = objInsp
  Set m_MailItem = objInsp.CurrentItem
  Set m_colInsps = Outlook.Inspectors
End Property

When a m_colInsps_NewInspector is fired, I see if I need
to add my button.  Things seem to go well up to this
point, but when I click on my button to launch my own
form, I get an error when I try and show the form
using .Show vbModal, Me.

I get error 371 which is:

The specified object can't be used as an owner form for
Show() (Error 371)

You must use an appropriate object with the Show method.

Can I not use my own VB form?  Do I have to make it am
Outlook Custom Designed form?