No sound after VOB set created!!

[joshwalden2000]

I have an AVI that is in 2 parts, both parts have the AC3 codec on them.... when i extract the codec from each they both can be played and the audio is correct on both pieces..... the first part works fine when i author the M2V and the AC3.... the second part doesn't work though!!, the actual AC3 file works (After trying it in Media Player) but it doesn't work as the DVD??? Anyone know why this is?????

Thanks V. Much