name csv-file with date in format yymmdd

[Geert]

Hi,

My csv-filename I have to send changes for different buildings. So I made the filename variable in the beginning of the script: 

8 Filename = os.date("%y%m%d")'2714_functietest.csv'

44 res, err = mailattach(ToServiceEmail, Subject, Message , Filename, csv, 'text/csv')

By executing the script I got error:
Resident_script: 8: attempt to call a string value
stack traceback

What am I doing wrong?