I have a Sony RDR-GX350

Question

I have a Sony RDR-GX350 DVD recorder. I want to combine titles on the playlist according to the instructions on page 65 of the manufacturer's manual. The only problem is that the instructions only work up to a point. After step 2 (Select "Edit" and press ENTER), in Step 3, I am told to select "Combine" and press ENTER again. However I am not offered that option to select. Can you assist?