Without seeing the code, its hard to determine what the problem is. I have an example of doing this in my book (VSTO for Mere Mortals), but since the book hasn't been published yet, I'll share a bit of the code here for you.

Things to keep in mind are:

• Rather than using ActiveDocument, you should use ThisDocument, which you can access from the user control by using the Globals class.
• This code adds the textbox to the current selection to give the user the opportunity to choose where in the document the textbox is added.
• Control names must be unique, so I've incremented the name of each control added by counting the total number of controls in the document.

If you have a button on a user control that you add to the actions pane, you can add the following code to the user control:

Public Class UserControl1

Dim ControlCounter As Integer = 0

Private Sub Button1_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button1.Click

Dim Selection As Word.Selection = _
Globals.ThisDocument.Application.Selection

Dim ControlName As String = "Control" & _
ControlCounter.ToString()

ControlCounter += 1

Globals.ThisDocument.Controls _
.AddTextBox(Selection.Range, 100, 50, ControlName)

End Sub

End Class

I hope this helps!

Kathleen McGrath
http://blogs.msdn.com/kathleen