That "Macros have been disabled" warning in Word 2010

That "Macros have been disabled" warning in Word 2010

I have been re-installing Windows and Word 2010. Everything works fine, except that Word 2010 does not seem to accept two custom macros which I use everywhere else. I am unable to get rid of the "Macros have been disabled" message after I have added the macro.
Two other Word 2010 installations that I created one year ago, load the macros while allowing me to set the standard macro policy to "Disable all macros with notification".
On this new installation, I am unable to recreate this behavior.
I imported the .bas file using the VBA window. The project folder structure looks the same as on the machines where it works: There is a "New macros" module under "Normal", containing only the macros I want to use.
I also tried to digitally sign the macro, which I cannot remember having done on previous installations, but still no luck.
Obviously, I have forgotten some step in order to make the macros load witout warning.
BTW, the macros are simple zooming functions which I assign to hotkeys:
Sub ZoomIn()
Dim iZoom As Long
iZoom = ActiveWindow.View.Zoom
iZoom = iZoom + 10
ActiveWindow.View.Zoom = iZoom
End Sub
Sub ZoomUt()
Dim iZoom As Long
iZoom = ActiveWindow.View.Zoom
iZoom = iZoom - 10
ActiveWindow.View.Zoom = iZoom
End Sub