Why doesn't pgAgent run my job every minute?

I have a job and I set the schedule to run every minute. However, it always skips the next minute after finishing the process, even when the process ends in less than one minute. The problem is that data is still arriving during that minute so when the job starts, it has to process two minutes of data. I'd rather have two 15 seconds runs, than one long 30 seconds run. **How can I make pgAgent run every minute?** In other cases when I set the schedule to every 3 minutes, pgAgent skips the 4th minute and starts on the 5th.