Scroller not visible until the scroll offset change?

[Zax]

Hello,

I'm designing a scroller for a scroll frame and I have a problem with the scroller itself: it is not shown until I activate the scroll, by click on the arrow-down btn or by mouse-wheel.
The path to my .tga image is valid because the scroller is well visible once it has been "manually activated".

This is my code:

fSlider.texture = fSlider:CreateTexture("$parentThumbTexture", "BACKGROUND")
fSlider.texture:SetTexture("pathToMyAddon.tga")
fSlider.texture:SetSize(16, 24)
fSlider.texture:SetTexCoord(0.25, 0.75, 0.125, 0.875)
fSlider:SetThumbTexture(fSlider.texture)

It's a lua-converted code from the following XML found on the net:

<ThumbTexture name="$parentThumbTexture" inherits="UIPanelScrollBarButton" file="Interface\Buttons\UI-ScrollBar-Knob">
	<Size x="16" y="24"/>
	<TexCoords left="0.25" right="0.75" top="0.125" bottom="0.875"/>
</ThumbTexture>

Thank you.