How can I get MS Word 2010 to display synonyms ?

I am using Mac OX. When I go for synonyms by clicking right on, it shows the synonyms option. but when I keep the mouse on that option though it shows the synonyms of that word but I cant click on them.. It shows with default action and I only can see them but cant use them. this is a big problem for me. please help me as early as possible. thank u.