FauxScrollFrame in pure LUA problem

[Zax]

Hello,

Sorry if it has already been asked but I encounter a problem with FauxScrollFrame.
In the past, I used this kind of frame with XML without problem, but now I'm trying in pure LUA.
When I click on the arrows to scroll, I have this error:

Interface\SharedXML\SecureUIPanelTemplates.lua:329: Usage: Cmdli_frameHisto_scrollScrollBar:SetValue(value, [treatAsMouseEvent])...

The problem seems to come from offset in:

frameScroll:SetScript("OnVerticalScroll", function () 
	FauxScrollFrame_OnVerticalScroll(frameScroll, offset, 16, Cmdli.scrollerUpdate)  -- "Cmdli" is my current namespace
end)

In previous XML version, offset wasn't defined and it worked (don't know why), and now I don't know what value offset should have.

Thank you for your help.