Problem putting 2 movies on one dvd+r. Anybody know about this?

I will go through the steps I took.

1. Took the dvd movies Dirty Work and Liar Liar and ran them through DVD shrink. I got them both compressed to fit on one 4.38 gb dvd+r.

2. Took the VTS files movie files from each, with each having 3. Put Dirty work VTS_01_1, VTS_01_2 & VTS_01_3 in a seperate folder. I then took the same 3 files from Liar Liar and renamed them to 4,5 & 6, so they would run in order after the Dirty Work files.

3. Went to IFO EDIT v 0.95 (dvd author)and selected create IFOs, which is at the bottom middle of the screen. Ran the files through this and it created VIDEO_TS.BUP, VIDEO_TS.IFO, VTS_01_0.BUP, VTS_01_0.IFO, which then showed up in the folder where I had the movie files.

4. I then went to NERO and chose DVD-video. I dragged all of the files from the folderto the VIDEO_TS on the left. I then chose to burn the dvd+r.

Once this was done, I played the disc and Dirty Work started at the beginning and ran through to the end. Once ti was over, Liar Liar started up, but appears to start from somewhere in the middle of the movie. It seems to run correctly to the end of the movie, but I don't know what happened to the first part of the movie. What is the cause of this? What exactly am I doing wrong?