Sounds and Preloaders [AS3]

So I have this preloader and some sounds I want loaded before the game starts. I have tried the standard 3 frame trick with the first frame containing the preloader graphics, the second frams containing an Asset holder movieclip (which contains all of the library symbols) and a 3rd frame that loads up after the preloader is done. All the library symbols except the preloader have “Export to first frame” unchecked.

Here’s my problem. I have the sounds placed in the AssetHolder movieclip (on separate frames for accessibility). When the game loads and I click the keys that should trigger the sound, I get an error saying “Invalid sound”. However when I check the “Export to first frame” box of the sound files, they work fine in game but load up before the preloader.

Also, most of the graphic symbols are arranged manually on the stage in different frames. They aren’t added to the stage via code. Would I even need an Assetholder type movie clip when they already exist in the timeline?

Any help would be greatly appreciated.