I am trying to import data from an .xls file containing date fields with european date format like dd.mm.yyyy

Importing the xls file the date column appears as a dropdown field. When I want to change it to a date field, I get the error message:

"One or more rows contain a value that´s not a date. These won´t be importet. Proceed with changing the field type?"

All the fields in the row have the correct format dd.mm.yyyy

What to do to import the european date field correct?