I am a Co-signer?

I co signed for a unsecure loan for my brother. He has been 30 days late a few times. He says that it shows up on his Credit Report. The funny thing is I dont even see it on my at all. If I am a co-signer why wouldnt it show on my credit report that I cosigned on the loan for him?? I dont understand this. Someone please help. This loan is actually 18 mos old. I have never seen this on report.