Cron job failure report

[torusturtle]

I have set up a cron job that should be executed every 5 minutes.
I selected 5 in the minutes section and all in all the other sections.

The cron generates an error message (which has nothing to do with ISPConfig).

The interesting fact is that I get the error only once an hour.

Does that mean that the error will only send once an hour or is this cron not executed every 5 minutes like it should be?