ContextException - populating drop down. (newbie question)

I map the selectedConfiguration attribute to the component context's selectedConfiguration so that I can access the value in the subsequent views.

On the current view, the selectedConfiguration corresponds to a dropdown. This exception gets thrown on the line :

ISimpleTypeModifiable myType = wdControllerAPI.getContext().getModifiableTypeOf("selectedConfiguration");

How can I populate a drop down if the context for that drop down is mapped to the component context.

com.sap.tc.webdynpro.progmodel.context.ContextException: AttributeInfo(ItemLaunchConfigurationView.selectedConfiguration): must not modify the datatype of a mapped attribute

at com.sap.tc.webdynpro.progmodel.context.AttributeInfo.getModifiableSimpleType(AttributeInfo.java:337)

at com.sap.tc.webdynpro.progmodel.context.Context.getModifiableTypeOf(Context.java:171)

at com.sap.netweaver.bc.uwl.ui.admin.ItemLaunchConfigurationView.wdDoInit(ItemLaunchConfigurationView.java:103)

at com.sap.netweaver.bc.uwl.ui.admin.wdp.InternalItemLaunchConfigurationView.wdDoInit(InternalItemLaunchConfigurationView.java:124)

at com.sap.tc.webdynpro.progmodel.generation.DelegatingView.doInit(DelegatingView.java:61)

at com.sap.tc.webdynpro.progmodel.controller.Controller.initController(Controller.java:215)

at com.sap.tc.webdynpro.progmodel.view.View.initController(View.java:388)

at com.sap.tc.webdynpro.progmodel.controller.Controller.init(Controller.java:200)

at com.sap.tc.webdynpro.progmodel.view.ViewManager.getView(ViewManager.java:645)

at com.sap.tc.webdynpro.progmodel.view.ViewManager.bindRoot(ViewManager.java:515)

Thanks a lot

Manish.