There's definitely dvd burners that can only burn + or -. But then there's some that can burn both, but to get full compatibility you may need to upgrade the firmware on your burner. Newer firmware versions can improve the burning ability of the burner & make them more reliable. Perhaps even increase the burning speed capability. Keeping in mind that there's newer revisions of dvd media on the market. By revision I mean the dvd group that develop them have brought out new standards ... & industry has adopted them for faster & more reliable dvd disks. But older burners need upgraded firmware to cope properly with them. I know this was true with my burner. Also some brands of dvd media work better with some burners & not others. Most burners will have their prefered brand of dvd media where all facets of burning are at their most efficient. I reviewed my model on a site that tests them with different dvd media. Here's an example of dvd media testing for my model of burner (this test was some time ago ... http://www.cdfreaks.com/article/204/5)