Hey santosh, can you walk through what you did? This will help others better assist you. I see the look up but I didn’t see any join conditions unless I missed them... In general the more details you provide the more likely someone will respond.
You need to join your "main" CountryCode column to your "lookup" CountryCode column and carry out an inner join. Your web service is erroring because you are returning every row of your lookup. REST services are only supposed to respond once per call. Of course you might want all of your lookup rows returned in one big XML output. If that is the case you need to set "All in one" to true in your response output. That will allow your XML to hold a look per lookup.
