Hello, I have the following problem with word 2000 and vba programming

I have placed a textbox control within a word document via VBA and the
accessible default objects. The control has been named to
TextboxNotice. This control should be shown or hidden via Button Clicks
from other controls or due to other program conditions.
I thought that I can do this with the .visible property - but this
property isn't shown in the poperty sheet of this control and
programcode like below always gives a runtime error 438. I have the
same problem with CommandButton objects. Whats going wrong?

Thanks in advance for helpfull informations

part of VBA program code from the word document:

Private Sub CommandButtonOn_Click()
TextboxNotice.Visible = True  <----- run time error
End Sub

Private Sub CommandButtonOff_Click()
TextboxNotice.Visible = False  <----- run time error
End Sub