That drive is a DVD-ROM drive. ROM=Read Only Memory. The drive model alone will tell you, it cannot burn anything at all. It just reads both types of discs. Burners are typically referred to as DVD+/-RW drives (read and write for both + and - formats). LG's internal writers come in models with number os the form GSA-4xxxxB or GSA-Hxxx. Do not buy any LG writer which has a model starting with GWA, GCA, GMA or similar. You will have trouble getting firmware support later.
So your drive is incapable of writing data because the hardware doesn't support it. I'm afraid you're going to have to take it back. I'm not sure who misled who in your case but unfortunately, that is the way it is.