Custom assignment block is not working when hidden

Dear All

We have created a custom assignment block and inserted in the opportunity overview screen as an assignment block.

This assignment block has validation date and last pipeline update date fields. Whenever we do some changes to certain

pipeline fields( say Origin,probability...) then immediately the field( Pipeline update date ) of the custom assignment block will be

updated with the current date and time( time stamp).

Now as per the requirement by default this assignment block has to be hidden( we do this using the configuration) and whenever

the user needs it he will add it on to the screen using personalize but the issue is whenever the assignment block is hidden and if

user changes any of the pipeline fields correspondingly the value for the Pipeline update date field is not updating.

We have done the corresponding coding in DO_PREPARE_OUTPUT.

Can you someone guide me why the code is not triggering when it is hidden, we need the fields should be updated even when it is hidden.

Regards

Anil