UIEnable works as designed.
Where are you trapping the UIEnable() event? The outermost pageframe?
If so, it'll never fire. UIEnable() is designed to only fire for objects contained within a page; therefore, including UIEnable code in at the general pageframe class level is pointless.

To see how UIEnable is designed to work, put the trap in an object inside the page, not on the outermost pageframe itself.

e.g., on a form with on object hierarchy as follows:

form                      - trapped events: Init, Activate
  pageframe1                   - trapped events: Init, UIEnable
    page1                      - trapped events: Init, Activate
      text1 (textbox)          - trapped events: UIEnable
    page2                      - trapped events: Init, Activate
      pgfInside (pageframe)    - trapped events: UIEnable
        page1
        page2

you'd get the following event flow

** ox=NewObject('testform','testlib')
TESTFORM.PAGEFRAME1.PAGE1.INIT
TESTFORM.PAGEFRAME1.PAGE2.PGFINSIDE.PAGE1.INIT
TESTFORM.PAGEFRAME1.PAGE2.PGFINSIDE.PAGE2.INIT
TESTFORM.PAGEFRAME1.PAGE2.INIT
TESTFORM.PAGEFRAME1.PAGE1.TEXT1.UIENABLE .T.
TESTFORM.PAGEFRAME1.INIT
TESTFORM.INIT

** ox.Show()
TESTFORM.PAGEFRAME1.PAGE1.ACTIVATE
TESTFORM.ACTIVATE

** select outer Page2, contains Pageframe
TESTFORM.PAGEFRAME1.PAGE1.TEXT1.UIENABLE .F.
TESTFORM.PAGEFRAME1.PAGE2.ACTIVATE
TESTFORM.PAGEFRAME1.PAGE2.PGFINSIDE.UIENABLE .T.

** select outer Page1, contains Textbox
TESTFORM.PAGEFRAME1.PAGE2.PGFINSIDE.UIENABLE .F.
TESTFORM.PAGEFRAME1.PAGE1.ACTIVATE
TESTFORM.PAGEFRAME1.PAGE1.TEXT1.UIENABLE .T.

>Hi,
>
>this is a Old Bug ? I see this on VFP6/7/8.
>
>On a VCX, a pageframe initialization events is:
>

>Page1.Init
>....
>PageN.Init
>* Now ActivatePage property is read
>* On any control on ActivatePage
>Uienable(.T.)
>....
>Uienable(.T.)
>Pageframe.Init
>.....
>Form.Init
>pageframe.ActivatePage.Activate
>Form.Activate
>.....
>

>I aspected
>

>Page1.Init
>....
>PageN.Init
>* Now ActivatePage property is read, but not events fire
>Pageframe.Init
>.....
>Form.Init
>pageframe.ActivatePage.Activate
>* On any control on ActivatePage
>Uienable(.T.)
>....
>Uienable(.T.)
>Form.Activate
>.....
>

>
>On SCX UiEnabled not fire, not before, not after;
>instead fire a Deactivate of the default page.
>
>Then, is hard to build a general pageframe, good on SCX and VCX.
>
>Fabio