Updates don't install

i have just put a clean install of Yosemite on a new Ssd in a 2010 MacBook pro. Then I installed logic 9 from discs. The update to 9.1.8 appears in the App Store but after downloading it does not install. I am left with 9.0.0 which does not run. Likewise main stage, wave burner etc. the update window shows then all updated but no new files to be found. The updates appear in the window again ready to be downloaded and yes I have downloaded them again. Groundhog Day.

anybody know what's going on?