Error: String Was Not Recognized as a Valid DateTime" Error in Web Access

After ticket creation the system get the following error :

String was not recognized as a valid DateTime.

I setted the system culture  ( en ) for  each  tps.config  files  and in web.config  

<configuration>

  <system.web>

  <globalization culture="en-GB" />

  </system.web>

</configuration>

Anyway I got error when i try to open a ticket alredy created