WPF MVV Command not working : i develop a app in WPF using prism 6 i try to update the date time with this command , i try to update the code without any successes
you can find the code in this URL:[code sample ][1] 


  [1]: https://1drv.ms/t/s!AuT6bv-RfbiewjVcmWMW45ndgf3s


any help ? 