Problem importing activities from excel

Hello all,

Here is the issue im facing;

I made my activity list in excel with each WBS codes with the exact codes in Primavera. I then made one new activity in Primavera, exported the xls file, added the "Activity ID", "WBS code", "Activity name" and "Duration" of each actvity, and made sure the "Duration" was formatted to text, but when I import it I get an Error message saying';

Excel Import log started : 14-Feb-19
INFO: Importing Global Data...
INFO: Importing Project Data...
INFO: Importing:
WARNING: TASK: Failed to resolve foreign key for field WBS Code with value NEWPROJ-7.Cons.Allb.Resd.St-A.Z-01.A-A1.Sust.Cnwr. Field cleared.

It has this for what I belive to be every WBS

Then it says;

ERROR: target_start_date is null for TASK ActivityID: St-A-Z-01-A-A1-3-0, Project: NEWPROJ-7

For what I assume is every activity.

I hope you guys can help.

Thanks,

Alex