Outlook 2013 Userform with block Error when not "Popped Out" - vba

Question

I have a set of macros that have worked in Outlook 2003, 2007, and 2010. In fact, it still works in 2013 except in a specific case.
The macro brings up a dialog box whenever you try to send an email - to tag the subject line with key words. The problem is, if I just started Outlook, and I bring up a new email or reply - the default in Outlook 2013 is to bring it into the former "Reading Pane" rather than in a new window. If I do not hit "Pop Out" and I try to send, my macro crashes with this error:
"Run-time error '91' Object variable or with block variable not set"
I tried to check for loading the form first - but it seem ANY call to my userform, even userform.show, generates this error.
Oddly, if I remember to "Pop Out" my first email, it runs fine everytime after until I close/reopen Outlook. Even if I don't "Pop Out" other emails. It's only on the very first one that this occurs.
Here's the beginning of my Initialize Event:
Dim Tags() As String
Dim T As Variant
Dim PC As Variant
Dim Rent As String
Dim Child As String
Dim nsourcefile As Integer
Dim email As MailItem
Dim PD As Variant
Dim Proj As String
Dim Desc As String
'Set email = Application.ActiveInspector.CurrentItem
Set email = Application.ActiveExplorer.Selection.Item(1)
'Checks to see if a project number (that's not on the list) may be in the subject already
If Val(email.Subject) > 10000 Then
TagMsg.Height = tall
TagMsg.NewProjID = Format(Val(email.Subject), "00000")
TagMsg.NewProjDesc.SetFocus
Else
'Set height of form (prior to pressing "More" button
TagMsg.Height = short
End If
Noticed I changed Set email = Application.ActiveInspector.CurrentItem to Set email = Application.ActiveExplorer.Selection.Item(1). This seems to have fixed it, but the VBA help states "Do not make any assumptions about the Item method return type; your code should be able to handle multiple item types or a ConversationHeader object."
Note that the form is being invoked by the ItemSend event.

Answer 1

First off, putting that code into the Initialize event wasn't a good move. Needed to be moved into a click event where it was actually needed.
Then, I found the code I needed from two other posts, combined and shortened them.
Working with current open email
https://superuser.com/questions/795831/outlook-2013-vba-refer-to-editor-in-reading-pane
Final result
Dim oInspector As Inspector
Dim email As MailItem
Dim oexp As Explorer
Set oInspector = Application.ActiveInspector
Set oexp = Application.ActiveExplorer
If oInspector Is Nothing Then
'Set email = Application.ActiveExplorer.Selection.Item(1)
Set email = oexp.ActiveInlineResponse
If email Is Nothing Then
'MsgBox "No active inspector or inline response"
Exit Sub
End If
Else
Set email = oInspector.CurrentItem
End If 'oInspector is Nothing
If email.Sent Then
'MsgBox "This is not an editable email"
Else
'Checks to see if a project number (that's not on the list) may be in the subject already
If Val(email.Subject) > 10000 Then
TagMsg.Height = tall
TagMsg.NewProjID = Format(Val(email.Subject), "00000")
TagMsg.NewProjDesc.SetFocus
Else
'Set height of form (prior to pressing "More" button
TagMsg.Height = short
End If
End If 'email.sent
Note: This still relies on the fact that it is called by the ItemSend event and the active or current item will be the email I just pressed "send" on.
Thank you, retailcoder for your comments.