[TYPO3-user-registration] Invalid date format for birth of date

[Christian Heisch]

Hi,
I am having a problem with the date format in the user registration.
Any way, that I am entering a date of birth, I get the error "Please enter a valid date in the format tt-mm-jjjj!". It's a german installation, so my translation may be inaccurate. Neither 10-10-1986 nor 10.10.1986 nor 10/10/1986 or something, it doesn't work.

My template constants look like this:

plugin.tx_srfeuserregister_pi1.useLocalCountry = 1
plugin.tx_srfeuserregister_pi1.enableAutoLoginOnConfirmation = 1
plugin.tx_srfeuserregister_pi1.dateSplit = .
plugin.tx_srfeuserregister_pi1.usernameAtLeast = 3
plugin.tx_srfeuserregister_pi1.formFields = username, password, gender, first_name, last_name, email, usergroup, address, city, static_info_country, zip, telephone, company, comments, disable,date_of_birth
plugin.tx_srfeuserregister_pi1.requiredFields = username, password, first_name, last_name, email, address, city, zip, date_of_birth
plugin.tx_srfeuserregister_pi1.confirmInvitationPID = 0
plugin.tx_srfeuserregister_pi1.enableAutoLoginOnCreate = 1
plugin.tx_srfeuserregister_pi1.enableAdminNotifyOnAdminAccept = 0
plugin.tx_srfeuserregister_pi1.enableAdminNotifyOnAdminRefuse = 0
plugin.tx_srfeuserregister_pi1.passwordAtLeast = 3
plugin.tx_srfeuserregister_pi1.termsUrl = 18
plugin.tx_srfeuserregister_pi1.file.templateFile = fileadmin/templates/sr_feuser_registration/template.html

I have no idea, where to look.
I hope, someone can give me a hint.

Regards
Christian