Frame damaged after cut

[wanttobefree]

Hello,
I'm trying to cut a *.vob file. So I open it (Avidemux 2.5.6) and I select the part to cut: from a frame I to another I. Then I cut and I save the file using "copy" for Video and Audio and "MPEG-PS" for Format. After saving, I don't know why, there are some damaged frames where the cut has been done (in the junction between the preceding and following frames).
Am I doing something wrong?

Thank you

[Agent_007]

If you want to remove a section, select it and use delete. And don't delete from I frame to another I frame. Delete from I frame to one frame before the I frame.