Sounds as if you have Office 2007 or 2010 - the English dictionary is not compatible with OE. You have to install a separate one. It's been so long since I did mine I can't remember the method I used :~
Various choices to fix it, Do a google search, copy and paste the following line into address bar:
oe6 french dictionary site:pcadvisor.co.uk/forums
This will give you all the threads on pcadvisor that offer solutions.