Rejection reason in SAP workflow

Hello All,

I am trying to give a popup for entering the rejection reason in user decision step. I have created a method and added the logic in that to call the text box. When I execute the workflow, I get the below error.

Below is my task binding:

The container also has value for requester

I have also tried giving initial value for the container field but still I get the same error.

Can someone please let me know if I am missing something?

Regards,

Sri.