Not true.
BTC writers with NicW's upcoming DVDInfoPro can change the booktype on DVD-R as well
Anyways, that's not the problem here. If the drive *can* read -R, then it's a media/burn quality issue. As the discs are TY, we can rule out media.
The LiteOn is notorious for poor quality QA and calibration on DVDR drives -- some are great, some are awful. I always recommend the Japanese brands currently for DVDR because most of the Taiwanese brands are the same. +R only works better on the LiteOn because it is easier to write a +R disc with a crappy drive calibration and get away with it.
The RV32 is a Panasonic isn't it? In my experience Toshiba and Panasonic drives spit +R media regardless of booktype -- my Tosh RDXS30 certainly does, as does my Panasonic portable.
You could try a couple of different types of -R media, but personally I'd say you need to get it RMAd if it doesn't work well with TY.