A date column in a table won't save the value after a correct date was entered
Community wiki answer:

There are loads of options/possibilities. See Datetime Format Models in the Database SQL Language Reference.

For example, if you have it set to DD-MON-RR, you should use 15-SEP-17.

RR lets you store 20th century dates in the 21st century using only two digits, as described in The RR Datetime Format Element:


  The RR datetime format element is similar to the YY datetime format element, but it provides additional flexibility for storing date values in other centuries. The RR datetime format element lets you store 20th century dates in the 21st century by specifying only the last two digits of the year.
  
  If you use the TO_DATE function with the YY datetime format element, then the year returned always has the same first 2 digits as the current year. If you use the RR datetime format element instead, then the century of the return value varies according to the specified two-digit year and the last two digits of the current year.
  
  That is:
  
  
  If the specified two-digit year is 00 to 49, then
  
  
  If the last two digits of the current year are 00 to 49, then the returned year has the same first two digits as the current year.
  If the last two digits of the current year are 50 to 99, then the first 2 digits of the returned year are 1 greater than the first 2 digits of the current year.
  
  If the specified two-digit year is 50 to 99, then
  
  
  If the last two digits of the current year are 00 to 49, then the first 2 digits of the returned year are 1 less than the first 2 digits of the current year.
  If the last two digits of the current year are 50 to 99, then the returned year has the same first two digits as the current year.