[Xrystal]

Ah, you need to redefine CargoPanel_Frame in each function you want to access it in as they are local to the function unless you set it outside the function.

plugin.setSelected = function( selected )
	if selected ~= plugin.selected then
		plugin.selected = selected;
                          local CargoPanel_Frame = _G["CargoPanel_Frame"];
		if selected then
		CargoPanel_Frame:show()
		else
		CargoPanel_Frame:hide()
		end
	end
end