Error while Spell Check

hi i am using VS2005 and Ajax2.0
when i click submit button it should check spell check,in that On “Spell Checker” pop up after click on “Add to Dictionary” button it is Giving Below Error exception.

EO.Web Controls Client Side Debug Message:
SpellChecker ‘ctl00_Mdi_SpellChecker’ has failed due to a server side exception. Click OK to see the exception message.
You can turn off this message by setting EO.Web.Runtime.DebugLevel to 0 (Not recommended for debug build).