Unable to find updates older than the current ones...WT@ is that?

having problem with wavelab pro:
10.0.40 is fine.
last month, i tried 10.0.60 and it killed my use of a cd/dvd burner
reverted to 10.0.40 and no more problem.
yesterday, i tried 10.0.70 and same problem.
now i want to try 10.0.50, and it’s not available anywhere…
is that for real? crazyly unacceptable indeed.