Agreed - try lower speeds. I bought a Pioneer BR burner last year (internal, BDR209-EBK) and some Verbatim BD-R DL (50GB) discs. Although the discs were rated as 6x speed for burning, I made half a dozen coasters at 4x and 6x speed. Once I started burning at 2x as recommended in the club.myce forum, they worked perfectly. In fact, some hardware testers recommend always burning BD-R DL discs at 2x speed even if they appear to work at 6x, on the grounds that the burn quality is higher at 2x.
I’d give 2x or 1x a go before giving up on the discs.
Bluto