AviSynth audio errors while converting with VDub x64

[klischee]

Hi

When I try to convert or decode audio (AAC, WMA) with Virtual Dub x64, I receive errors by AviSynth after a couple of frames.

System: Windows 7 x64
Editor: VirtualDub 1.10.1 x64
Wrapper: ffmpegsource2 x64

Example:
I open up an MP4 (AVC/AAC) with an avs looking like this: "ffmpegsource2("D:\video.mp4", atrack=-1)"
Everyting is fine till now, the video gets displayed in VirtualDub. (AVI Information, MediaInfo)
If I select e.g. frame 0-100 and encode the file to xvid/lamemp3, it works fine, also the audio gets encoded correctly.
But when I select e.g. frame 1000-1500, I receive one of the following errors:



"Avisynth read error:
Avisynth: unknown exception"


"Avisynth read error:
FFAudioSource: ReadPacket unexpectedly failed to read a packet"

This also happens with other formats like WMV/WMA. I always can render or play the first seconds of an audio stream with VDub, but after a couple of frames I receive one of both errors. Without audio disabled there are no decoding/rendering errors.

Can you help me?