Personally, I wouldn't waste time with CD-RW media. Not worth the expense. I just use CD-R as I'm never going to write over it....
Some writeable optical drives are persnickety about the media you feed them. I suspect that's what you've encountered..
tje
But I don't want to be constantly buying new CDs. I can take a five-month old backup this way, and use it for a new backup without wasting money.