I am writing a sh file to take screen short and want to schedule in crontab
but when i run the .sh file it run OK no problem happens but when try to schedule it in crontab i got an error like

import: unable to open X server `' @ error/import.c/ImportImageCommand/366.

my .sh file is like

#!/bin/bash

filename='ABC'

import -window root $HOME/Desktop/$filename.png

any idea how to solve it i tried with

which import

it is showing

/usr/bin/