hiCreateTabField

Hello,
attempting ot create a form with many tab fields one inside the
other, I get the following error
*Error* hiiCopyScrollRegion: scrollRegion nested within itself: -
page1
a sample of my code is given bellow

Tab1 = hiCreateTabField(
?name 'Tab1
?tabs '("Label1" "Label2")
?tabPlacement 'top
?fields list(FieldList1 FieldList2)
)
Tab2 = hiCreateTabField(
?name 'Tab2
?tabs '("Label3" "Label4")
?tabPlacement 'top
?fields list(FieldList3 FieldList4)
)
Tab3 = hiCreateTabField(
?name 'Tab3
?tabs '("Metal Layers" "Via Layers" "Manage Layers")
?tabPlacement 'top
?fields list(list(list(Tab1 0:0 500:526))
list(list(Tab2 0:0 500:526))
FieldList5)
)

Anybody knows if it is possible to create a tab inside another tab, or
if there is something wrong with my code. I also attempted to add the
first 2 tabs (Tab1 and Tab2) each in its own Scroll Region and then
add the Scroll Region in the final Tab, but had the same results. Any
suggestions?