Dear Ma'am, 
As mentioned in the comment section, I got the disclaimer - "It is showing one or more field names used in the report are no longer valid. If you are changing the name of a field in your datasource, please type a new name in the field." This was followed by :

" One or more connections did not refresh or the refresh operation was cancelled. Would you like to refresh the remaining connection? " 

Though the data gets updated after selecting Ok. But please help me find out why is this happening? 

Thank you so much for your quick response. It means a lot to me. 

Tushar Soni