Retrieve ErrorColumn Name in Error Flow SSIS

Hi All,

I am trying to retrieve the ErrorColumn name from the error raised in a dataflow. this is how i set up.

in the list column names i have written the code from the link.

http://angelia-thompkins.blogspot.com/2011/05/retrieving-ssis-error-column-names.html

but its raising the below exception. 

how can i solve this to retrieve the ErrorColumn name .

Thanks in advance