Image rollover not working in a block

Hi everyone,

For some reason my image rollovers are not working in the bottom right block (facebook and twitter icons). Basically when you roll your mouse over the icons they should change to a slightly lighter colour.

I’m not sure why it isn’t working. It works fine in dreamweaver. I have copied the dreamweaver code into a html block in CS Cart admin, and then for some reason it doesn’t work on my main page.

Does anyone have any ideas?. Thanks