Software update not working!

I have a weird problem. All this while the SU was working just fine. However; things began to turn weird when there was the Safari and Leopard security update available yesterday, but it didn't show up in my software update. I had to manually download them off Apple's download page. Now, I suppose there are two more updates and the Software update still says my system is up to date. I have no record of it ever installing these updates neither is it showing the new ones. I tried every possible way but alas. How do i fix this?