WoWInterface - FauxScrollFrame Offset Issues

I am having issues with the ScrollFrame setting it's offset when updated.
It is a list of the 40 raid members, showing 20 at a time and here's the update function.

Code:

Source RPS.lua:

FauxScrollFrame_Update(RPSRaidFrameScrollBar,40,20,20);

Code:

Source RPSForm.xml

<OnLoad>

              FauxScrollFrame_Update(RPSRaidFrameScrollBar,40,20,20);

</OnLoad>

<OnVerticalScroll>

              FauxScrollFrame_OnVerticalScroll(20, RPS_RaidFrame_Update);

</OnVerticalScroll>

<OnShow>

            RPS_RaidFrame_Update();

</OnShow>