addedAfterSprintStart() not Recognizing Sprint

[Brendan]

The function addedAfterSprintStart() works for all of our group's sprints except for one.  Let's say the sprint in question is 'Sprint_X'.  When I execute the string "Sprint in ('Sprint_X')" all appropriate issues are shown.  The sprint also appears correctly in the Agile Sprint Report.  However, when I execute  the addedAfterSprintStart() function I get this error: No Sprint with that name could be found for this board.  

This is very similar to a previous question: https://answers.atlassian.com/questions/14209855.

Any ideas why this is happening?

Thanks

[Nuwan]

Hi

Navigate to your custom fields and see the sprint field is LOCKED in default.  so you cannot access the field. sprint is a automated field in JIRA if you put a issue into a sprint the field "sprint" automatically updated. you can unlock this filed using simple sql but I feel it not safer to unlock the sprint field. need further investigation to find out is there any issues with unlocking the sprint.

[Brendan]

The sprint field is not locked. Thanks for your time though.