On Jan 22, 2013, at 3:09 PM, Jean Pierre Malrieu wrote:

attempt to assign value to unknown key: 'masterObjectAndRelationshipKey'.
This WOComponent does not have an instance variable of the name masterObjectAndRelationshipKey or _masterObjectAndRelationshipKey, nor a method of the name setMasterObjectAndRelationshipKey or _setMasterObjectAndRelationshipKey
  at com.webobjects.appserver.WOComponent.handleTakeValueForUnboundKey(WOComponent.java:1781)
     ... skipped 8 stack elements
  at com.webobjects.appserver.WOComponent.setValueForBinding(WOComponent.java:910)
  at er.directtoweb.components.ERD2WSwitchComponent.setExtraBindings(ERD2WSwitchComponent.java:189)

How old is your Wonder? I see setValueForBinding called on line 190 after explicitly checking hasBinding(key) on 189.