String was not recognized as a valid DateTime.

hello
i use a label to display date in format "d/M/yyyy" by using this line
but if the user adjust the region from windows control panel "Short date :dd-MM-yyyy" then label display the date in this format dd-MM-yyyy and the error "String was not recognized as a valid DateTime." appear


how can i display date in format "d/M/yyyy" without return the format from region setting?


thank you