getNextApprovers4 returns null value

I am using the following code and this returns null value. I am able to test the AME using the test run in AME and it returns the right approvers.

I am using a custom workflow to invoke the custom AME transaction.

Please help.

declare

l_next_approver                    AME_UTIL.approversTable2;

l_is_approval_complete      VARCHAR2(1);

Begin

ame_api2.getNextApprovers4

                (applicationIdIn=>101,

                transactionTypeIn=>'FORM62APPR',

                transactionIdIn=>'10128',--item key

             --   flagApproversAsNotifiedIn => ame_util.boolean.False,

                approvalProcessCompleteYNOut => l_is_approval_complete,

                nextApproversOut=>l_next_approver);

dbms_output.put_line(l_is_approval_complete);

End;