how to set and get context varaibles in datapower   

I have created one multi protocol gate way service which is making call to one loop back xml fire wall service.

It is takes the soap as the input message and gives soap output.consists of 2 transform actions(one is transform binary another is transform).

transform binary action takes the soap body part as input and gives back the string as the output which i am setting(means iam giving the context variable name in the action output) in the conetxt variable.

In the 2 nd transform action iam trign to take the conetxt variable as the input but it is neither getting the value nor setting it.

if any one knows how to set and get context variables please help us to solve the problem