Check to make sure there are no errant spaces in either of the string values you’re comparing. Also, make sure that there is only one identity with that value for that attribute. If IDN finds more than one identity matching the search results (displayName = Ritu Raj, in this case) then correlation will fail.
Lastly, displayName is not a great attribute to rely on for correlation. If possible, I’d suggest using something like an employee number or ID or an email address, etc. Display names are not necessarily unique and aren’t as strictly typed as other attributes like employee numbers/IDs or email addresses.