Is it worth helping out a seperate department within your company , when ur not being recognized for ur effort

I'm a contractor and the department I work for doesn't give me alot of work to do. So I applied for a different position, I was rejected for the position, but offered a chance to help out within the group that I applied to. Now the group barely acknowledges me or my effort. I'm tired of helping this group - for free - and not being valued for my talents and efforts.