Auto-screenshot script works except for when using Cron

[Joshua Marpet]

Ubuntu 16.04
Shutter 0.92

The following script works fine from a command line.
It works when installed as a cron job in Gnome-Schedule, and triggered manually.
It does not trigger every <time interval> when cron should trigger.

Use case: want to auto-screenshot the screen every few seconds, and save a screenshot to a folder as a date-time named file. The below script is to do it once, just as a test. If I could get it to work, then I'd have it loop and sleep and wake and screenshot, and sleep and wake ....

Am I screwing something up? :) Thanks!

#!/bin/bash

cd /home/jimuser/Pictures/
 for i in {1..1}
do
    shutter -f -e -o './%y-%m-%d_%T.png'
done