AVI Appending with VDub

How do I properly Append avis with vdub. I have two avi's that have ac3 5.1 audio. In vdub Direct spream copy is selected; and when i append files and then play it the second part is out of sync, the audio is ahead by almost 9 seconds. When playing files separate the sound is ok. Thanks

Is it only the second joined file that goes out of synch?

Yes, only the second Thanks for the reply but I figured it out how to fix it In case somebody has similar problems it could be done with vdub or vdubmod. the problem with my files were that the first clip had different sizes for video and audio streams so I just cut the video of first file to match the audio lenght in vdub range option

sorry, different sizes I meant different lenghts