Groovy script not working in Create transition but working in other than create transition

[Balvant Biradar]

Hi Team,

I wrote script to copy multi select list value to multi group picker custom field.

Same script is working in other than "Create" transition but not working in Create transition and getting below error while running in Create transitions

2017-09-05 17:12:22,486 ERROR [workflow.ScriptWorkflowFunction]: 
***********************************************************************
************** 2017-09-05 17:12:22,486 ERROR [workflow.ScriptWorkflowFunction]:
 Script function failed on issue: null, actionId: 1, file: <inline script>
 java.lang.NullPointerException: Cannot invoke method setCustomFieldValue()
 on null object at Script204.run(Script204.groovy:33)

Please advise me what could be cause for different behaviour of script and I am new to this Groovy scripting

[Balvant Biradar]

Hi Team, 

sorry to bother you, It got fixed by changing position of script from top to bottom

Thanks,

Balvant