rndc flushname works from command line, but not from bash script

Question

I am banging my head against the wall here trying to figure this out. I have an automated DNS propagation system I am trying to build internally, and everything works except rndc flushname. If I do this at a shell prompt

$ sudo rndc flushname /var/lib/bind/$domain.hosts
$ sudo rndc reload

This works

Also if I create the following bash script:

#!/bin/bash
domain="some-domain.com"
# Do stuff 
rndc flushname /var/lib/bind/$domain.hosts
rndc reload

And run it

$ sudo bash myScript.sh

It works.

This command is not working if I assign the script to a cron job though IE

$ sudo crontab -e
.... 
 ....
/5  * * * bash /etc/bind/dnsCron/dnsCron.sh

Why does rndc work from straight shell. It also works manually called in a bash script. But when called from crontab it doesn't reload? All commands are run through sudo and the crontab is also running under root. I am not sure what the issue is here? Is there another method to call rndc flushname ?