I have set up two calculated items, which are workinig correctly:
http://screencast.com/t/Wa6D9nE7ASO

Then I want to add the third one, which would calculate the rate between the items (let's call it success_rate).

The formula is the next:

last("userAccount.host.login.finished.false.sum.600")/last("userAccount.host.login.started.false.sum.600")

As soon as I add this, zabbix started the calculation and the value of the success_rate is always 0.

As soon as I would update the formula to this:

100*(last("userAccount.host.login.finished.false.sum.600")/last("userAccount.host.login.started.false.sum.600"))

It would be calculated correctly, but I don't need the number between 0 and 100, I want the number between 0 and 1.

The funny thing that the other rates I'm trying to calculate are calculated ok. And I don't have any ideas how the problem items differs from the one which are giving me the working rate. But for the 4 items I spot from the different hosts, the situation which I've described takes place.

There are no errors in the logs.

Any thoughts how to overcome that?