Seeking reason why one transparent GIF works GuiCtrlCreatePic but another doesn't

I found the following code in a forum post by newbiescripter, which displays a transparent gif "crosshair".

#include <WindowsConstants.au3>

$x = @DesktopWidth/2 - 13/2
$y = @DesktopHeight/2 - 13/2

GUICreate("", 13, 13, $x, $y, $WS_POPUP, BitOR($WS_EX_LAYERED, $WS_EX_TOOLWINDOW, $WS_EX_TOPMOST))
GUICtrlCreatePic("target.gif",0,0,13,13)
GUISetState()

Sleep(3000)

It works great... with the gif file included in newbiescripter's post. I was able to modify the gif in CS6 for my needs but I'm really curious why another gif that I created from scratch in CS6 does not display with transparency in the same script. (I know how to create transparent gifs, and mine opens in CS6 with transparency intact.) I'm probably just knackered from long hours but I give up and submit my question here despite the probability of embarrassment. 

See attached. "Crosshair.gif" is the one that works. "Target.gif" is the one that doesn't. "Target.psd" is the original PSD file. (oops, not allowed)