Add audio don't work on ffmpegX

[petwes]

Hello, my goal is to remove the internal subtitle from a DVD (folder), and add an external SRT. I have an MacPro with lion and use ffmpegX 0,0,9y-L with the newest binaries.

To do that, i followed this steps: I have demuxed the VIDEO_TS folder with DVD Demuxer because ffmpegx don't pull out the subtitles.
What i've got left is the m2v video file, the ac3 audio file and the subtitle files (that in this case i don't use).

In ffmpegx i'v added the m2v video file in the source format.
In the target format i select the DVD ffmpeg engine preset.

But when i try to add the external audio (AC3) file in the audio tab, and click preview in the options tab (below), i don't hear anything.
I have converter the AC3 to MP2 but nothing work. I also tried "invert mapping". What do i do wrong?

Second question: is it possible to add the external srt subtitle in the same step? Or have i to convert video/audio and add the subtitles separate?

[Case]

You shouldn't add the .m2v and the .ac3 to the encoder, but use the Tools section instead.

In the Tools tab, select the Mux sub-tab.
Add the video and audio using the designated buttons.
Uncheck Author as DVD.
Mux. This will create a DVD-compliant MPG file.

Switch to the Author sub-tab.
Add the .mpg (from previous step) and .srt using the designated buttons.
Author. This should output a VIDEO_TS folder.

Open the VIDEO_TS folder in Apple DVD Player for a test drive.
Your subtitles may need to be manually activated to show.