Why can't I add words to my custom dictionary on Word for Mac 2008?

Every time a word comes up and I don't want to keep doing spell check for it, I want to add it to my dictionary. Every time I spell check, It says custom dictionary not available. Any ideas?Why can't I add words to my custom dictionary on Word for Mac 2008?
You need to turn this capability on. This is from Office 2008 for Mac All-in-One For Dummies page 233

1. Choose Word %26gt; Preferences

2. In the Authoring and Proofing Tools section, choose Spelling %26amp; Grammar

3. In the Spelling section click the Dictionaries button

4. Select the Custom Dictionary check box.

5. Click OK to close the Custom dictionary and then click OK again to close the Spelling and Grammar Preferences pane.



Now you can right-click or control-click on any word with a red squiggle and add it to the custom dictionary.