Automation for JIRA math with customfield on a branch rule

[vidoq]

I have a rule:

• Trigger: Transition to Done
• Branch rule JQL condition: resolution is EMPTY and cf[10600] is not EMPTY and assignee = currentUser()
• Edit issue field cf[10600]: {{issue.customfield10600}}-1

I need to get all issues, where customfield_10600 not empty (it's a number string)

then in every issue I need to change this customfield, minus 1. So if it were 2, it become 1 etc...

My rule works good, except {{issue.customfield10600}}, it returns - NULL. So after my rule stop, all customfield in relevant issues changed value to -1.

What did I wrong?

[vidoq · Accepted solution]

oh, I found my problem. I should use 

{{issue.customfield_10600}} nither smart values..