Primavera P6 Total Float frozen and incorrect?!

All,

Was wondering if you could help me with the recent issue with P6.

In a particular project we had around 11 separate critical paths all linked to their individual milestones. However the float around the 9 and 10^th critical paths for some inexplicable reason did not move regardless of how far forward or back you moved the critical activities or changed Milestone dates.

From moving activities way in the future to be done a lot earlier or being moved 2 years back, this failed to show any difference and still stated that it was 13 days positive float regardless. This matter was only resolved by putting a final “project complete” Finish On milestone that all end milestones from all of the separate critical paths tied into. Only then did it show a changing float pattern for these 9 and 10^th Critical path activities. Can anyone explain why this happened?

Any help you can offer would be greatly appreciated,

Thanks,