Did you use it for font sizing? If so, this might be a better alternative:
If you use it for colorization, using
<font color="CC0000">Text in color</font>
Should work fine. As you can see, we are nog using a hashtag # in front of our hexcode. Could it be that this was the issue? If not, could you please show me your code so I can see what the issue might be? 
Kind regards
Sam