It is quite possible that your particular DVD drive cannot read double-layered (DVD-9) DVDs. It may be a physical limitation of the drive itself.
If yours is a desktop PC, I recommend you replace the DVD drive with a new one. Cost is like $20 and it is easy to do yourself.
If yours is a laptop, I recommend you buy an external DVD reader/writer. These connect to a USB port and cost about $25 or so.