Jiri,
My apologies for not answering sooner. This issue was corrected. It was the way I entered the initial command. set system root-authenticaion plain-text-password. I had that entered in incorrectly.
The correct script should be:
edit
set system root-authentication plain-text-password
password
password
delete snmp communityold-string authorization read-only
set snmp community ne-string authorization read-only
commit
This issue has been resolved.