Binding error with standard Business object

HI Folks,

I would really appreciate ur concern for getting this doubt clarified.

At decision step i m using method to display a custom application and I need to pass some values into that method since it is not possible I thought of creating an attribute in the business object and populating it and using inside the method. When I am trying to bind the business object attribute in the step above this decision to pass the values it states with the following

error "Expression refers to a data object that cannot be changed, for example, a constant, a system field, an object attribute, or a method that cannot be changed. A binding cannot use this data object as a target."

I need to populate the value so that I can display the custoom application / screen every time in the loop.

Thanks in advance for the help.

Regards,

Krishna Mukthineni