gridLayout: Unable to save selected rows in gridRowLayout to a local variable

Hi everyone,

Please help check whether I'm doing anything wrong in below code. I'm having an editable grid with data source is a data subset local variable. In gridRowLayout I already provided the id for identifying, and save the selected ID into a blank local variable. But when I select each row, it's value is not stored into my local variable. I also tried with fv!index but that did not work either. 

Below is the data subset local variable. I indexed into it's data.fileId field.