Multiple condition in Conditional Field doesn't work
I was in the same trouble.  

I just found that you can use one condition and use "Values input mode" to  Only one of these values (XOR) and Set of Values to the ID or Text of the value of the field you want.

Check that : http://www.interworks.com/blogs/gbivens/2010/06/04/tricking-drupal-webforms-allowing-multiple-options-same-key-value

EDIT : Here a picture