Selectable read speed differs from time to time?

[hineck]

Hi. I own a TSSTcorp SH-S223C DVD+RW drive that I'm using with DT Pro (trial).
My problem is that sometimes DT allows me to read a specific disc (original non-copy) only at 6x speed, even though the drive supports 12x. If I eject the disc and enter it again then sometimes DT will allow me to select 6x, 8x, 12x, 16x and sometimes it only allows 6x - it seems completely random what speed I am allowed to select, but I did notice that whenever Daemon Tools allows 6x only, the disc doesn't spin up to a hearable speed when inserted like it does when DT allows the other speeds.

As a side note I can say that Alcohol 120% ALWAYS allows me to select a wide range of speeds (1x, 2x, 4x, 6x, 8x, 10x, 12x, 16x, 18x, 20x, 22x).

Why does it change over time in DT?

[Blazkowicz]

Alcohol doesn't read the speeds from the disk and drive itself.

I guess you are using the latest DT Pro.

[hineck]

Alcohol doesn't read the speeds from the disk and drive itself

That's my interpretation as well. Still doesn't explain why the reported speed changes.. with the same disc? - Does the drive detect it's compatibility with the current disc and report a speed then?