I have tried to replicate your problem without any success. My charts work just fine.
You may have a currupted preference file. Creating a new Keynote Preferences File might help. This is done by deleting the old preference list and restarting the application:
Finder > User > Library > Preferences > com.apple.iWork.Keynote.plist (delete this file and restart Keynote)
I have a similar problem. Every time i try to add a Chart (2d or 3d) Keynote crashes with the message "unexpected error...". After that i am not able to restart keynote only a complete uninstall allows me to open keynote again but the bug is still there.
In the console are a lot of messages:
"NSMap get: map table argument is NULL"
"NSMap Insert: map table argument is NULL" (NULL -> = Zero (german)
16.04.12 09:44:17 Keynote Fehler auf höchster Ebene: NSInvalidArgumentException : *** -[NSCFArray insertObject:atIndex:]: attempt to insert nil
(error on highes level...)
Can anyone help? I need keynote for work so its´s really bad.
THX in advance
System: MBP 17 early 2011; 10.6.8
Keynote ´09 Version 5.1.1 (1034)