Ganeshwari,
I sympathize with these … The likely problem is a typo somewhere. In essence Studio is telling you that it looked in the Dictionary and could not find the entry (key) you were calling and thus doesn’t have a Value to work with. 90% of the time there is a typo that sneaked in.
Open your OC assets and copy the asset in question into the config file, and ensure 100% this is correct. then copy the name from your config file into your in_config(“HERE”).ToString part and that needs to match 100%. in my experience it is that one stupid typo that foils it all.