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I am not up enough on DVD to know if this could be a factor but something to look into.
This new format, among other things, resulted in DVD-R being unofficially referred to, in error, as DVD "minus" R. However, DVD "minus" R is not correct, according to DVD-R consortium recommendations; it is, in fact, a dash (i.e. DVD "dash" R). DVD-R and DVD+R technologies are not directly compatible, which created a format war in the DVD technology industry.
To reconcile the two competing formats, manufacturers created hybrid drives that could read both most hybrid drives that handle both formats are labeled DVD±R and Super Multi (which includes DVD-RAM support) and are very popular.
I am not up enough on DVD to know if this could be a factor but something to look into.