That doesn't seem to be some software from Thomson Reuters. Sure it connects to a Thomson Reuters feed (or a TREP) but that's really all that can be said from the screenshot.
Also, what exactly does "Not able to get correct closing price for this security" mean? Are you getting a price at all? Have you previously been able to get able to get correct price for this security?. You are using field TRDPRC_1 but that field doesn't contain the closing price unless you request the price at exactly the right time of day. Seems like a dangerous strategy. It may have worked before but if you do the snap (it is a snap, isn't it?) at another time than what you have previously done (say inside the exchange's opening hours) then you'll simply get the latest traded price at that time, not the closing price. Albeit 15 mins delayed because you are using a "/"-RIC.
If you suspect a technical problem: I bet your application has a log file somewhere ? That file should be able to provide you better answers. If you can't find such file then you'll need to contact the vendor of the application.
I hope this helps.