How to calculate production hours?

[vignesvar]

Hi all,
i'm using Dimensional Package cross table report. I want to calculate the production hours. Person as row, budget/hours for work_effort_purpose_type_id and production hours are column in cross table. It is calculated by the sum of feature, support and retainer and reduced by bugfix hours. These four (feature, bugfix, support,retainer) are sub-category of work_effort_purpose_type_id. Here  I gave that query it is not working for that data in bugfix and show exact result of others. That is

if([WORK_EFFORT_PURPOSE_TYPE_ID (Custom)]='Bugfix') then (total ([Business Namespace].[TimeEntry].[HOURS])-[Business Namespace].[TimeEntry].[HOURS]) else (total ([Business Namespace].[TimeEntry].[HOURS]))

Where data presented in bugfix Production hours are 0 else showing exact results. Also I was tried case too. Help to resolve this issue.
Thank you.