Not able to set the assigned group with the script

[udayasuriyan keerthika]

I tried using both this method to set the value in assigned group and assignee:
issue.setCustomFieldValue(assignedGroup_cField, assignedGroup)

issue.setAssignee(defaultAssignee)
or
def changeHolder = new DefaultIssueChangeHolder()
assignedGroup_cField.updateValue(null,issue,new ModifiedValue(issue.getCustomFieldValue(assignedGroup_cField), assignedGroup), changeHolder)In history it is showing the correct value of assigned group, even in log it is showing the correct value but in the issue the assigned group is not updated.

[Nic Brough -Adaptavist-]

You'll need to show us all the relevant code, not just the bit that tries to write the variables to the issue.  Show us the parts where you define the variables, reindex the issue, where the code is running and what the field type is.