Updated from 5.0.14 to 5.0.16, guest additions image won't..

[Winxp-on-Macos]

V.B. installation was updated from 5.0.14 to 5.0.16, host is OS X, guest is Ubuntu Desktop 14.04LTS, 64Bits.
Usually following the version update the guest additions are to updated as well to be in sync with V.B. app regarding version number.
However, this time mounting the guest additions image does not succeed, see attached screenshoots.
Is this a known problem?

[frank]

Did you download that .iso image manually? Is the .iso image file corrupt? Can you mount that file manually?

[Winxp-on-Macos]

As usually, the V.B.-bundled taken, invoked from V.B.GUI - host short key, Devices, Insert Guest Additi.....
No iso file in possession.
No idea how to mount it manually.

[Winxp-on-Macos]

Well, I accomplished a try to find the way of manual mount the Guest Additions iso image on used host: OS X.
V.B. Virtual Media Manager lists this iso image in optical discs group, however user can't access this
when adding iso image to the virtual machine (v. machine's settings, Storage) - apparently as far as OS X host
the V.B. is maintaining this iso for own purposes, not for user's usage - and the iso addition to v.m. dialog
asks for disk file, not for stuff visible at V.M.M level.
Easy access to iso image on level of OS X file explorer is also not straightforward as the image as embedded
in app binary file. So I had to dive into app package and extract iso manually to desktop, or such.
Than back to v.m. settings, Storage and iso was added to v.m. IDE controller.
Please confirm or disagree the above procedure.

All the above followed by v.m. boot and user log-on.
Iso disk is visible in Nautilus but not mounted.
A try to mount in manually using Nautilus completed with same error message as reported initially.
What's wrong?

Another 14.04 LTS v.m. of same Ubuntu updates status does not show these probs. For me this
is the evidence all is fine with Guest Additions iso image embedded in V.B. installation (the App)
as both v.m. use same host and same V.B. installation.
One hint more, every time a new version of V.B has been downloaded we test the checksum, sda.
As for 5.0.16 the test completed successfully.

[Winxp-on-Macos]

Root cause has been found, solution too, then applied. Problem solved.
Linux kernel extra modules package for used kernel version was missing.
Reinstallation using Ubuntu package management helped to fix the problem.
Background
For this Ubuntu guest a clean-up is made periodically, means kernel versions
been made obsolete by Ubuntu updates (security, Ubuntu recommended updates)
are periodically deleted by administrator using Ubuntu package management.
Otherwise one day the hard disk storage space consumption arise to alerting levels.
Apparently the last clean-up ran to far in that way that kernel extra modules for current kernel version
were removed too.
Thanks for all your help!