Are there items in your speadsheet where the items shown are blank or NULL? If your Service Desk form is looking for these and it's not there the log is going to give you this result. Doesn't mean the import didn't work necessarily, just letting you know something was missing.
Thanks for the info, I did manage to create a new excel and added it to the data import. The import log now shows no error but the data in the reference list is not being mapped.
What could be the problem? ( As I have also checked the data in the reference list and manager names which match the excel sheet data).
If you are running version 7.5 without SP1 then make sure you have the hotfixes applied. One fix is for Problem 5419 which related to data imports not mapping related records properly. You can download the hotfix from here: Service Desk 7.5 Cumulative Hotfixes.
Thanks Stu... It worked well