Compatibility between Nero 6 and Nero 7?

We have some drives that came with Nero I’m trying to get our app working with these drives. But the Nero web site shows only the Nero 7 SDK with a footnote saying that the new SDK is compatible with Nero 6.

What I’m seeing is that the code written with the Nero 7 SDK works on systems with Nero 7 installed but not on systems with only Nero 6 installed.

The mode of failure is that drives reach the “start write” phase but write progress never advances past 0%.

Can anyone here offer any clues as to what may be going on? Is there any way to make this pairing work? Or do we have upgrade our licenses to Nero 7?

Alternatively, is there any way to get the Nero 6 SDK?