You may not see your results on that immediately. My experience after sending back a Work Unit is that the credit doesn't show for a few hours, but it will.
You can also print out a certificate for what you have done at any time by clicking on your personal stats. (the number of WU's or Points you have)
This is what one of them looks like:
Below this is a Work Unit certificate. I resized it so that it wouldn't hurt the bandwidth at the site much, but you can see that they are a real certificate from Stanford. They appreciate us very much!
(and this right here is a "SOUTHERNISM")
"I GUARANTEE YA!!!"