Small help with AceGUI layout

[onesock]

I am trying to follow a simple example posted by the AceGUI author. I think I am missing something simple.
Ultimately I am trying to have an independent frame that contains large textbox that scales to size.

function CreateScrollFrame(widget, height)
    local scrollcontainer = AceGUI:Create("SimpleGroup") -- "InlineGroup" is also good
    scrollcontainer:SetFullWidth(true)
    if height then
        scrollcontainer:SetHeight(height)
    else
        scrollcontainer:SetFullHeight(true)
    end
    scrollcontainer:SetLayout("Fill")

    widget:AddChild(scrollcontainer)

    local scrollFrame = AceGUI:Create("ScrollFrame")
    scrollFrame:SetLayout("Flow")
    scrollcontainer:AddChild(scrollFrame)

    return scrollFrame
end

initImportGui = function ()
    local frame = AceGUI:Create("Frame")
    frame:SetWidth(500)
    frame:SetHeight(600)
    frame:SetTitle("Import/Export List")

    local scrollFrame = CreateScrollFrame(frame)
    
    local editBox = AceGUI:Create("MultiLineEditBox")
    editBox:DisableButton(true)
    editBox:SetLabel("")
    editBox:SetFullWidth(true)

    scrollFrame:AddChild(editBox)
    editBox:SetFullHeight(true)

    return frame
end

I commented out the actual editbox and the frame defined as "SimpleGroup" that has "SetFullHeight(true)" does not scale to the height of the containing frame. Any idea what I'm missing?