Transaction console data along with the approver name.

I have created a report to fetch the all the transactions details from the transaction console, along with the transaction id , process name and approvers name and some more columns. The whole report works good and displaying the correct output, the issue arises with the approver name column as it not fetching the approvers name for multiple processes in the report for some process the approver name is coming in the report but for most of the cases the approver name is not coming in the report and it comes as null values. I have used 'fa_fusion_soainfra.WFTASK