Welcome to the forums.
Why re-import highly compressed media? Go back to the original and export with the codec you really want.
If you have no other choice then demux the .M2T file into separate video and audio files and import those into PPro.
Are you using the DL (Adobe Dynamic Link) to get your PrPro Project into Encore, or are you Exporting from PrPro and then Importing that file into Encore?
If the latter, then Export as elemental streams, i.e. Video-only in one file, and Audio-only in the other. In Encore, Import the Video-only file as a Timeline, and the Audio-only file as an Asset. From the Project Panel (in Encore), drag the Audio file to the appropriate Timeline. Encore often has trouble with muxed files (Audio & Video multiplexed).
If the former, Encore should see your Sequence(s) and you do not need to Export/Import anything.
Thanks for help, Eddie and Hunt. The problem I exactely have is that I edited some AVCHD-material and exported it as about eight .m2t files each of about 10minutes duration. Now I want to build a Bluray disc in Encore with these eight .m2t-files. But Encore doesn't play any sound (so I think the Bluray disc won't have any sound either, will it?). Because I deleted the original AVCHD files I can't edit the whole project once again (what I don't want anyway). So my idea was to re-import it to Premiere to change the audio file (from Dolby to PCM - to see if this audio file would be playbacked in Encore?) But even Premiere does not play the audio file of the m2t-file. But the external programs as Arcsoft Mediatheater 3 play the files correctly, so the audio of the m2t must be o.k. I think it is a problem of my CS4, isn't it?
Hope I made it a bit clearer (sorry my English is not that great...).
The English is great - no worries there.
OK, you have the muxed m2t files. For some reason, neither Encore of PrPro (the parent program of these files) will play the AC3 component.
Ann Bens has mentioned the AC3 Filter (maybe in another thread). Have you tried it. If has worked for some, though a few had to resort to other means.
Another tack, since you cannot Open your old Project, without the source media files, would be to de-mux one of the m2t files. This would give you the two "elemental streams," an m2v (Video) and the AC3 file. Try the old "manual" way of Importing those into an Encore BD Project. Unfortunately, I have zero experience with de-muxing HD material, so have no recs. on programs to use/try. Others can probably step in and help you here.
There have also been several threads on CS4 and AC3 material. Unfortunately, most came before the forum changeover, so seaching for them might be a bit tedious. There might be some easy fixes in those slightly older threads.
Though the number of BD authoring programs is still a bit slim, maybe one of them would do a better job with your muxed file, than would Encore. Might be worth looking into doing a trial of some, and testing. Again, as I do not do BD yet, I don't have any recommendations on which programs you should even consider.
Good luck, and please post back with your findings,
My guess here is version 4.0.1. giving the trouble.
Exporting to DD.
You're probably on to something there. IIRC, there WAS an issue with one of the updates, "breaking" something with regards to AC3. I had forgotten about that.
Because I deleted the original AVCHD files
Lesson learned there, huh?
Just NEVER do something like that. ALWAYS keep original media on a shelf somewhere - via hard drive, data disk, video tape, whatever - along with the project file and everything else you'll need to rebuild if you ever need to.