Hi,
moved to the correct category as this problem is not related to Vulnerability Tests at all (Please see the About the Vulnerability Tests category description for the purpose of this previous used category).
For the problem itself a starting point could be to compare the current used versions of the OpenVAS/GVM packages with the GVM-9 (stable, initial release 2017-03-07) releases.
If those are not matching the versions your distro packages are providing you could contact the maintainer of the packages to get updates or build the newer versions from source.