fontString:SetFont()

[Platine]

I have an object from game to which I assign text:

object:SetText("my text")

I can also assign a font to it right away:

object:SetFont(My_Font, size)

But some objects don't allow me to assign a font so explicitly:

attempt to call method "SetFont" (a nill value)

The object receives, for example, the function:

for _,GTxtframe in GossipFrame.GreetingPanel.ScrollBox:EnumerateFrames() do

How to specify the exact name of the fontString element of object?