I think you should reconsider and set it as Date data type. If you got an error, possibly one or more of your entries are not valid dates? Just a guess.

Within your database... You might be able to do this by creating a new field in your table as a DATE data type. Then create an update query and convert your kodeabsen field to date, using your database (Access, SQL Server, something else) conversion functions, updating the new field with the conversion. If that works, then you can delete the field kodeabsen and rename your temp field to kodeabsen. Once that is done, your sort will work as expected.

Another option is to use a database conversion from text to date in your query.