Word 2010 - Shading paragraph background
The background colour only affects the actual text and paragraph (which the gutter on the left of the bullet points is not technically a part of).
You'll probably have to wrap the block you want shaded in a table cell and then use Borders and Shading to set the background colour for the entire cell.
The answer to the issue is in the very next tool, "Borders and Shading".
- From the drop-down menu choose "Borders and Shading..."
- Click the "Shading" tab
- Choose the desired "Fill color"