[DVD-o-matic] Question/problem re: video trimming (0.89)

Hello all, I recently tried to cut a bit from the beginning an end of an mp4 source file in DVD-o-matic, which did not seem to work correctly. For my first try, I entered the start and end frame numbers (as seen below the video windows of DVD-o-matic) of the part I wanted to encode and "encode all frames and play the subset" as method. This resulted in the whole file being converted, just as if I didn't enter anything. For my second try, I entered the number of frames I wanted to cut from the beginning and the end of the video and selected "encode only the subset". Now, the *audio* was cut at the right point, but the video played from the beginning again. Additionally, I saved the project and loaded it at a later time. Now, the "Start" and "End" fields were set to "100" each, which bears no resemblance to what I had input into the fields before saving (750 and 251, respectively). How is this trimming supposed to work? What do I have to enter into the fields to get 750 frames cut from the beginning and 251 frames cut from the end? Any help is appeciated. Greetings from Germany Kasi Mir