can't get margin-right to work

[bluecaterpillar]

I must be missing something pretty obvious here. I need to put some space to the right of an image, but not to the left. So in CSS I have:

.rightspace{
margin-right:10;
}

And in my code, <img class="rightspace" href... etc. etc.

But, no space appears. I have tried making it 50 to see if there is a difference, but it's always the same. I can't use hspace because I need it to be flush with the left margin.

Thanks, Rebecca

[Kravvitz]

Unless the value is 0 you must specify a unit.
.rightspace{
margin-right:10px;
}