Flash CC Publish Animated Gif ignores looping sequences?

I'm just learning Flash so apologies in advance.

I can't seem to get an animated gif that won't loop--I only want it to play once.

Here is what I'm doing, using Flash CC Pro (latest):

1. Create an .fla file, all set to go, looks good
2. Go to Publish Settings, target is set to Flash Player 11.8, unchecked everything but GIF Image
3. Inside there, playback is set to "animated"
4. Repeat times, set to 1
5. Smooth is checked.

Have tried adding an action script to one layer after researching that trick, doesn't seem to work. Animation does have symbols as movie clips inside it.

Any help is appreciated for this newbie, thanks!