input element in web dynpro java not working

Hi,

Iam new to webdynpro java. iam trying on external context mapping example from sap help.when i run the application i have assigned a context to a input element that should be accessed by another other component's window view .when i follow steps given in diagram for external context mapping when i run the application i am not able to enter the data into the input textbox.it became read only.plz suggest me a good example for external context mapping and some times i am not able to enter a value for input field when i assign a context attribute to it.i have assigned a node context to the input element.

Thanks and regards

prasad