Why can't iMovie be updated from App Store or from updater?

Question

In 2011 I purchased the iLife '11 package on CD for $80 directly from Apple. Since then I've updated the various iLife Apps without incident, until yesterday.
I  downloaded the iMoved 9.0.6 Updater and attempted to update v 9.0.4 to 9.0.6. The Updater throws up an Alert: "The version of iMovie installed on this Mac must be updated through the Mac App Store yadda yadda yadda."
Well, I didn't buy iLife, or iMovie, through the App Store but I went there and attempted to update iMovie. Naturally, it isn't in my list of purchased items, nor does it appear on the Update page. However, the App Store knows it is on my Mac because the purchase button is now an "Update" button.
So even with Dirty Harry's 45 aimed right between my eyes, I'm feeling lucky and I punch "UPDATE."
Bam! New Alert: "You have updates available for other accounts To update this application, sign in to the account you used to purchase it."
Thank you Apple! I don't have another account, or any other accounts. One account is enough! I don't need no stinking other accounts.
First Apple screws the pooch by turning Final Cut Pro into iMovie on Steriods, and now to update iMovie I have to log into an account I don't have.
Adobe Premiere here I come.
While I can actually do without iMovie, I'm sure the next time I try to update another item from the iLife suite, I'll run into the same illogical problem, so better to solve it now.

Answer 1

Dear Shade247,
When you bought your MacBook, did you get a restore DVD? Perhaps that DVD will restore iLife - I think there is a software restore disc that comes with the machines.
The only way I was able to fix my problem was to dig out my original iLife DVD and reinstall iMovie.
However, in doing so, the install also reinstalled iPhoto, but actually trashed it. For some reason deselecting iPhoto was not a custom install option. So, I had to then reinstall iPhoto as well. 
Of course, once iPhoto was fixed and iMovie 9.0 was installed, and both working, I still couldn't update iMovie because v9.0.1 was the minimum requirement.
So, I had to scroll through pages of prior Apple updates until I found the iMovie 9.0.1 installer and download it. After 9 was updated to 9.0.1, the current 9.0.6 updater worked fine.
I can't wait until Apple realeases a new version of iPhoto and iMovie so I can go through this all over again.
Apple listen? Don't hold your breath!
Good luck!