Cacti NaN values

Daniels Pitkevičs asked:

Firstly, when I create cacti graph using data input method (PHP script) is does not create rrd file which it should do. Still, when I copy command which is shown when I turn debug mode on and run it manually, rrd file is created. After that graph is shown but all values ar NaN.
I looked in cacti.log which gives me nothing, permissions to needed folders are set to 777, my php script returns me data in format :, for example, humidity:20.0.
Device status is up. Everything, as I think, must be correct.
Poller_output table in mysql is with max approximately 4000-5000 rows, but it is being truncated by Cacti, so it is not the problem.
What else can I do? Any suggestions?

My answer:

There are a LOT of variables that could cause it. Best thing to do is:

First, wait for the next poll. A graph can’t be generated until there are at least two data points, and NaN will always show after the first poll.

Second, go through the whole debugging process in the Cacti documentation.

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