DVD-lab (chapters, and video stream problem)

[alexVS]

I worked with DVD-lab for a long time, but just found out some strange problem. During import of chapters, some of them were missing on DVD-lab timeline.

I imported frame numbers, that I took from m2v-video file using VirtualDudMod. I took only I-frames.

Before that I made m2v in Womble Mpeg Video Wizard, joining small 10-minutes fragments one-by-one into large file.

It looks like in junction points GOP structure is incorrect.
For example:
End of clip 1: .......IBBPBBPBBPBBPBBII
Begin of clip 2: BBIBBIBBPBBPBBP........
End of clip 2: ...........PBBPBBIBBPBI
Begin of clip3: BBIBBPBBPBBPBBIBBP..........

Does it mean that Womble Mpeg Video Wizard produces incorrect MPEG2 video stream in joining points or is there a problem in DVD-lab, placing chapters in such stream?