Making a field Read-Only while a specific sub-task is open

[CLINTON E_ SMITH]

We are using JIRA issues to track work and estimates, so we have the need to make the estimate at the issue level read-only while the sub-task related to developing a new estimate is unresolved.  So far, I've tried using a Behaviors script on the estimate field, but it doesn't seem to actually make the field read-only.  I'm hoping I'm just missing something simple.

Here is the Behavior I have tried so far:

def ROMe = getFieldById('ROM Estimate')
def subTasks = UnderlyingIssue.getSubTaskObjects()

subTasks.each {
 if (it.getIssueType() == 'Test CoS' && ! it.getResolution()) {
 ROMe.setReadOnly(true)
 } else {
 ROMe.setReadOnly(false)
 }
}

JIRA Version - 7.1.9

ScriptRunner Version - 5.1.6

[Alexey Matveev]

Reace

it.getIssueType()

With

it.getIssueType().Name